THE UNIVERSITY OF ILLINOIS LIBRARY 358.1 lb»36t ^-•’• ! t: v - >.- v: Msam TACTICS AND TECHNIQUE ARTILLERY Vol. / Prepared by The Artillery Sub-Section THE GENERAL SERVICE SCHOOLS FORT LEAVENWORTH, KANSAS THE GENERAL SERVICE SCHOOLS PRESS Fort Leavenworth, Kansas 713— 9-21-22— 2M 19 2 2 \ \ \ ' . Digitized by the Internet Archive in 2016 https://archive.org/details/tacticstechnique01usar memora: TEE GENERAL SERVICE SCHOOLS port Leavenworth, Kansas, 16 August, 1924. MEMORANDUM FOR: Command, and General Staff Class, SUBJECT: Errata sheets for T & T Artillery, 1* For the coming year the following should be issued with Vols. I and II, T & T Artillery: "Changes and Errata, T & T Artillery, Vcl I," as now printed, with two lines on page 2 deleted; (page ISO, paragraph 21 (a), lines 6 and 7). - "Changes and Errata, T & T Artillery, Vol II," as now printed, "Addenda to T & T Artillery, Vols I and II," as now printed, - "Changes and Errata T & T Artillery, Vols I and II," as shown below. 2, Changes and Errata in TT Artillery, Vols I and II, 16 August, 1924; Fage Vol I Paragraph Change 12 32 Plate II Plate- IV Under corps artillery delete "(Separate regt not a part of corps arty proper)," Under army artillery delete "(Not a part of army arty proper)." Corresponding changes should be made throughout the text. The regiment of antiaircraft is now. a part of the corp 3 artillery, and the antiaircraft brigade is a part of the army artillery » Delete, Replace by new plate to be issued separately. 53, 54: P Plates VIII &: Delete. Replace by new plates to be IX : issued separately. 99 12 Change to read as follows: "32, TA. CTICA L CLASSIFICATION OF A RT ILLERY K'SfTiC NS . - a. Artillery may be in posi blun~ or in readiness . b. An artillery unit is said to be ln*~ position when the pieces are in position and ready to fire and the necessary system of observation and communication has been established. 8-18-24/bmmd 2 Page Paragraph. Change <5, An artillery. unit is said to be posted in r eadiness when the pieces, limbe"'I - or coupled, are held under cover near a position for possible immediate action, but ready to move quickly to another locality if the development of the tactical situation should require it. The point selected for posting a unit in readiness should be centrally located with reference to the possible positions in which it may be ordered to go into action* During the time that the unit is posted in readiness, reconnaissance is continued and all other possi ble preparations are made that will hasten entry into action when the situation requires it," Vol II 196 Plate IX Delete, Replace by new plate to be issued separately. R. H, ALLEN, Assistant Commandant, 8-18-24/bmmd Page Glos- sary 2 4 11 11 11 12 12 32 Changes and Errata Tactics and Technique Artillery Vol. i Paragraph 18 (b) *Line 2 4 Last sen- tence 8 (e) (2) 5 and 6 Change Delete “generally.” To read “The corps chief of ar- tillery performs this duty for the corps commander.” “212” and “56” to “2i%” aqd 23 (c) 5 Delete “independent.” 23 (d) (1) 7 23 (d) (2) 5 Above “3 regiments 75-mm. guns (motorized)” insert “1 Brigade of Brigade Headquarters.” “1 Regiment 16-inch guns” to “1 Regiment 16-inch howitzers.” Plate I Note “3d and Maintenance Sections” to “5th and Maintenance Sec- tions.” Plate II Lower right hand sec- tion: Between 3d and 4th rectangles insert: “1 Brigade 75-mm. guns GHQ Re- serve 3 Regts (Portee)” and delete “3 Regts (Portee)” at top. Plate IV (columns) “Extreme 1. 75-mm. French gun: “8000” to range “8700.” yards” “Time to em- 7. 240-mm. howitzers: “10 to 24” place . . to “3 to 24 v.” Ditto 8 . 6-inch trench mortar: “2 hours to 3 weeks” to “4 hours to 3 weeks w.” “Days march, miles Delete this column. -2 Pape Paragraph *Line Change “Remarks” Add the following two: “v Minimum time has been low- ered since the World War by batteries in this country.” - “w To install a battery in a trench area where work must be done after dark and parts and am- munition must be carried through approach trenches by hand, from 3 to 4 weeks may be necessary.” 38 9 small print In 2d line: “80” to “30.” In 3d line: “30” to “80.” 51 10 5 and 6 “Batteries report, etc.” to “Bat- teries report to battalion muni- tions officer and battalion mu- nitions officers to regimental munitions officer by telephone.” 54 Plate IX Draw dotted line from “Army Ord Officer” to “Corps G4” and mark “copy.” 102 18 (b) 2 “IV” to “IX.” 107 25 (c) 2 “battery” to “better.” 115 6 (b) (1) 4 “below” to “on previous page.” (2) 7 “(A & B)” to “(A’ & B’) .” (4) (c) 2 & 5 “B” to “B* ” and “A” to “A’ .” 130 21 (a) 6 & 7 Delete sentence beginning: “The Signals.” 151 10 (a) 2 “72” to “70.” 154 17 (a) 2 “map of” to “map or.” 161 13 (b) 2 “supOrting” to “supported.” 164 16 (a) last “batter” to “better.” 169 2 (c) (7) 1 “Company” to “Battery.” 192 22 15 Insert “and tactical” after “tech- nical.” 220 9 (a) 2 (on page) “required” to “requires.” (b) 5 after “6000” insert: “yards (for the 50% zone).” 223 252 16 (a) (1) 4 (d) and (e) Last sentence Delete sentence. Delete both subparagraphs. — 3 — Page Paragraph *Line Change (f) “(f)” to “(d).” 253 4 (d) (2) Delete subparagraph. (3) “(3)” to “(2).” 268 6 (b) (5) 2 Insert “observation” between “brigade” and “posts.” NOTE. — *Number in “Line” column refers to number of line in paragraph or subparagraph designated, not to number from top of page. 1264 — G. S. Schs., Fort Leavenworth — 8-8-23 — 1800 Addenda to Tactics and Technique of Artillery Volumes I and II ARTILLERY FIRE SUPPORT, PREPARA- TION AND ANTI-TANK DEFENSE Prepared by THE GENERAL SERVICE SCHOOLS Fort Leavenworth, Kansas 1923 THE GENERAL SERVICE SCHOOLS PRESS Fort Leavenworth. Kansas 214 - 9 - 1 - 23—1600 THE GENERAL SERVICE SCHOOLS Fort Leavenworth, Kansas September 1, 1923. The principles and doctrines relating to artillery fire support, artillery preparations in the attack, and the use of anti-tank artillery published in this pamphlet express the views of the General Service Schools in the premises and will be observed in the conduct of all instruction. R. H. Allen, Assistant Commandant. Approved : HARRY A. SMITH, Commandant. Table of Contents Paragraphs Section I. — Forms of Artillery Fire Support 1-9 Section II. — Artillery Preparation in the Attack 10-11 Section III. — Employment of Anti-tank Artillery 12-13 Section I Form of Artillery Fire Support Paragraphs Part A. — Defense 1-5 Part B. — Offense 6-9 PART A The Defense Paragraph Deployed defense 1 Position defense 2 Zone defense 3 Principles 4 Doctrine 5 1. Deployed Defense. — a. In deployed defense, the kind of fire to be laid depends on the tactical scheme of defense. The artillery defense depends primarily on: (1) Observed fire on targets of opportunity, used when possible to the exclusion of organized fire, and, (2) Organized fire, prepared for emergencies, and when observation is impracticable. Whenever possible, data for this kind of fire is corrected by registration. b. When original atmospheric data cannot be obtained, standing barrages for close defense cannot be accurately laid, and are dangerous. Due to the unsettled conditions during the first hours of the occupation of a line or posi- tion, patrols or troops in front, etc., adjustment close to the lines to be defended becomes impossible. Due to lack of precise knowledge of the enemy’s dispositions before his attack is launched, counter preparation is limited to special designated objectives. c. In the counter attack, the principles of offensive fire apply. 2. Position Defense. — a. In position defense, there is time to prepare the artillery defense, which depends pri- marily upon : — 6 — (1) The use of observed fire to the exclusion of organ- ized fire when conditions so permit. Prior registration is obtained when practicable. (2) Organized fire when observation is impossible. b. The artillery promptly attacks by observed fire all enemy targets, utilizing quick methods. After making suit- able arrangements for observation, the artillery prepares organized fire (primarily counter preparation) for use when observation fails or the situation demands. c. The next fires arranged are organized fires asked for by the infantry, which may be in the form of standing barrages or concentrations. Standing barrages generally are prepared to be laid in front of the covering forces, and, later on, in front of the battle position. Concentrations may be laid in these places also, or, frequently in between, on any lines of entry between centers of resistance, or other organized places of local defense. 3. Zone Defense. — a. The principles which apply to the position defense apply in general to the zone defense, with the modifications noted hereafter. Observed fire, based on prior registration, is always used when possible. The following relate to the organized defensive fires : (1) Shallow zone . (a) Concentrations and standing barrages in front of the security, observation, and delaying systems, and in front of the battle position. (b) Concentrations between the covering and delaying areas and the battle position on probable lines of hostile penetration. (2) Average zone . (a) Concentrations and standing barrages in front of the outpost area, the delaying area and the battle position. (b) Concentrations, between the outpost and delaying areas, and between the delaying area and the battle position, all on probable lines of hostile penetration. (3) Deep zone . (a) Concentrations and standing barrages in front of each of the outpost, delaying, and battle areas. — 7 — (b) Concentrations between the outpost and delaying areas, and between the delaying and battle areas on prob- able lines of hostile penetration. b. In the zone defense, a most careful system of counter preparation is developed, based on information obtained from maps, aerial photographs, location of enemy works, and known and probable dispositions of the enemy. c. In the defense of zones organized in great depth, it is necessary for the artillery to occupy successive positions. In order that effective fire may be delivered promptly from these positions, it is necessary that basic firing data be computed for each position prior to occupation. d. Until the unorganized position of deep zones are organized, it is useless to prepare organized fires in front of them, but reconnaissance of the terrain should be made by the artillery in order to determine artillery positions and kinds of fire that may be executed from them. 4. Principles. — a. In all situations, the most effective and most desirable method for the use of artillery is direct attack by heavy concentrations of observed fire on the visible or definitely located enemy. b. Where observed fire cannot be obtained, use is made of organized fire. On the defensive, this includes concentra- tions and standing barrages. c. Counter preparation is most valuable and should be fired whenever due warning of an attack by the enemy is obtained. d. The artillery defense of a line or position is by organ- ized fire in the form of concentrations or standing barrages, to meet unforeseen attacks or unfavorable conditions of visibility which may render observed fire impossible. e. In cases where lack of visibility prevents observed fire, the advance of the enemy along lines of penetration between centers of resistance, strong points, and similar places, is opposed by concentrations of organized fire laid on suitable places. /. Since an attack is ordinarily made in depth, concen- trations searching a considerable depth as an- organized fire are more often preferable. The advantage lies in the fact that a succession of ranges gives certainty of securing some — 8 — effect by producing a series of barriers through which the enemy must pass, whereas the standing barrage forms but a single barrier, which is quickly traversed, frequently with very small casualties. The effect of successive concen- trations on the morale of attacker is greater than that of a standing barrage, because the enemy is in doubt as to where successive volleys will fall; whereas the position of a standing barrage is plainly defined and may be crossed in a single swift rush. It is not sufficient that the attacking front line only be held under fire. To gain success, support- ing troops must follow, hence an attack on them by artillery assists in weakening the driving force of the enemy. g. The standing barrage, when used, is utilized by lay- ing an intense fire in strips on or near places (such as stream crossings and lines of wire) which form natural or arti- ficial obstacles and which, in themselves, tend to retard or hold the attacking troops on the line on which the bar- rage is falling. To prevent dispersion, it should be laid only on the most sensitive fronts. h. Thin barrages are practically useless. They cause few casualties, waste ammunition and may give inexper- ienced infantry a feeling of false security, which may re- sult in disaster. i. If, for psychological reasons, the infantry desires a standing barrage laid in its front, the artillery should make it dense while it lasts, thereby not only aiding the infantry morale, but weakening that of the enemy at the same time. The great amount of ammunition consumed by frequent re- sponses to unnecessary calls for barrages and other organ- ized fire must be considered by all concerned. j. Even when conditions indicate an opportunity for reliance on observed fire, organized fire must be prepared for use when observed fire is not practicable. k. Secrecy is preserved as to the positions of the bat- teries as well as the places upon which they are to lay organ- ized fire. On this account, occasions for registration may be greatly limited. 5. Doctrine. — From the above principles may be de- duced the following doctrine : a. Observed fire is used whenever possible. — 9 — b. Organized fires are used when observed fire cannot be obtained, and must be prepared early for emergencies. c. Counter preparation and concentrations form the bulk of organized defensive fires . d. Standing barrages, although of limited application, are prepared to meet special situations . PART B The Offense Paragraph Rolling barrage 6 Concentrations 7 Principles 8 Doctrine 9 6. Rolling Barrage. — a. Advantages. — The advan- tages claimed for a rolling barrage are as follows: It pins the enemy to the ground all along the line, and protects the troops from short range hostile fire and local counter attacks immediately prior to an infantry assault. It stimulates and maintains morale of troops which follow it. It covers those targets which are initially unknown and which will not be discovered until the attack is launched. It marks a definite line for the infantry to follow. Its execution is mechanical and does not require as high a degree of training on the part of the artillery per- sonnel as do other forms of artillery fire support. It gives the infantry more intimate fire support. No observation is necessary. It screens the advance of the infantry by smoke and dust. It affects adversely the morale of hostile troops, es- pecially when they are inexperienced. b. Disadvantages . — The disadvantages alleged for a rolling barrage are as follows : It requires an enormous and uneconomical expenditure of ammunition, which is not readily obtainable except in a stabilized situation. — 10 — It limits initiative and flexibility of maneuver of attack- ing infantry. The exact regulation of its fire by observation is impos- sible. It requires a long time for its proper and exact prepar- ation and coordination. Its density is uniform throughout, instead of placing heavy fire on important points. It fails to protect troops from the fire of hostile troops located beyond the barrage. It is dependent upon accurate maps which may be dif- ficult to obtain. It may run away from the infantry. It lacks flexibility of fire — too rigid. It results in a dispersion of effort; therefore, it is not sound tactically. It gives the enemy indications of movement. It requires a very large number of guns. For a given amount of artillery and ammunition, it limits the front of the attack. Under certain conditions it becomes dangerous to the infantry it is covering. 7. Concentrations. — a. Advantages. — The advan- tages claimed for concentrations are as follows : They permit powerful and demoralizing local effect on important targets and lighter densities on unimportant ones, therefore great flexibility of fire; at the same time avoid waste of fire on unoccupied areas. They are more economical in ammunition expenditure than the rolling barrage. They frequently offer opportunities for observed fire on known targets. They permit more flexibility to meet changes in tactical situations occurring after the initiation of the attack. They can be better adapted to varying rates of infantry advance, should unforeseen conditions render a change neces- sary or desirable. Fire can be opened promptly without elaborate calcula- tions. They frequently are not dependent on maps. — 11 — They allow infantry greater initiative and flexibility of maneuver. They permit infantry to use their rifles and auxiliary arms to greatest advantage on definite local targets. They allow enfilade or oblique fire. The surprise element is more practicable than with the rolling barrage. They require fewer guns for a given front. They are less affected by withdrawal of batteries for forward displacement than are rolling barrages. They may be held on a strong position to neutralize it and permit the infantry to pass it by. b. Disadvantages . — The disadvantages alleged for con- centrations are as follows: Through inaccurate information, they may be misplaced and fail to properly cover the advancing infantry. The psychological effects are less than in the case of rolling barrages. They require greater skill in making accurate adjust- ments and, therefore, may result in limited effect on small targets. Unless concentrations are fast, dense, and cover quite a wide area, the enemy can avoid them by moving elsewhere. Unless timed concentrations are used, they require very efficient communications. Timed concentrations may re- strict the movements of the infantry. 8. Principles. — a. A rolling barrage to be effective, must be of sufficient density. This density is dependent on the number of guns available and their rate of fire. A thin barrage wastes ammunition and does not give the infantry the support expected. b. The basis of the rolling barrage is the 75-mm. gun. An effective barrage requires approximately one battery per hundred yards of frontage, with a sustained rate of fire of not less than two rounds per gun per minute. c. Except for local actions of minor units, a barrage should be thickened by additional 75s, which may fire shrap- nel and smoke, and by heavier calibers, which fire concen- trations in advance of the true barrage line. The machine guns and auxiliary arms of the infantry are also used to deepen the barrage. — 12 — d. Where progressive concentrations can be used suc- cessfully, the rolling barrage should not be utilized. e. The rolling barrage is especially useful under the following conditions: (1) When a deep penetration is to be made through a highly organized defensive area. (2) When it is necessary as a factor to sustain the morale of inexperienced or badly shaken infantry. (3) When the details of the local defense of the enemy have not been well determined. (4) When there is an ample amount of artillery to- gether with a plentiful supply of ammunition. /. The rolling barrage is not possible in the earlier phases of a meeting engagement and is not to be expected in the later phases. Sometimes it may be employed in the attack of a prepared position, but its most frequent use is in the attack of portions of defensive zones. g. The preferable form of artillery support is by ob- served progressive concentrations. This form of fire is flexible and is best adapted to meeting the varying tactical conditions of the battlefield, is economical in the use of am- munition and guns, is best adapted to celerity, permits the density of artillery fire to be adjusted to meet the character of targets to be neutralized, and, frequently, is independent of maps. h. The better the liaison with supported infantry, the less need there is for the rolling barrage, since fire power can be more effectively concentrated on decisive points. 9. Doctrine. — From the foregoing principles, the fol- lowing doctrine may be deduced : Observed fire , when practicable, is the most efficient support artillery can give an attack. However, it is often necessary to employ prearranged organized fire in the form of concentrations or of rolling barrages. Observed fire is used much more than the latter, but at times the rolling bar- rage is advantageous, hence it is retained as one of the methods of artillery support. » -13- Section II Artillery Preparation in the Attack Paragraph Principle 10 Doctrine 11 10. Principles. — The following principles in relation to the artillery preparation in the attack are presented as the principles accepted by the General Service Schools as deduced from modern artillery experience : a. (1) Unlimited preparations will be rarely used and will be confined to those cases where a certain amount of destruction is considered absolute necessary before an attack can be launched. (2) Limited preparations will be used preceding most attacks. (3) Preparations may be omitted altogether, under favorable circumstances, in order to obtain complete sur- prise. Against a defensive position, strongly defended by wire, this procedure will seldom be possible unless the in- fantry is supported by sufficient tanks to make the necessary breaches in the wire. b. An artillery preparation should never be ordered without a distinct mission as to targets and effects desired. c. Fire of extreme precision is not practicable for a limited preparation. Quality of fire is compensated for by quantity of fire. d. Neutralization of hostile artillery is of primary im- portance in an artillery preparation. e. No definite rules to cover all conditions can be laid down as to the number of guns required to neutralize effec- tively a given number of hostile guns or batteries. /. Complete neutralization of artillery, or other hostile elements, cannot be expected. The degree of neutralization obtained is dependent upon several factors and varies be- tween wide ranges. g . The principal factors affecting the length of the artillery preparation are the surprise element; the extent to which tanks are to be employed for making breaches in —14— the wire ; the strength and morale of the hostile forces ; the extent, strength, and importance of hostile defensive ele- ments ; the artillery means available to the attacker ; the state of the ammunition supply ; and the accuracy of fire. h. Generally, the length of preparation will be greater as the strength of the forces engaged and the extent of the hostile defensive organization increase. i. No definite rule to cover all cases can be laid down as to the duration of the artillery preparation. The length in each situation must be determined from a consideration of all the existing factors which affect it. j. The fire delivered during the execution of the attack is, in effect, a continuation of the artillery preparation. 11. Doctrine. — a. In general, attacks will be preceded by limited preparations, the length of which will vary be- tween a few minutes and several hours. b. The length and other details of artillery preparations are determined by consideration of a number of factors, the principal ones being: surprise, available tank support, extent of hostile defensive organization, and artillery means available, including ammunition supply. Section III Employment of Anti-tank Artillery Paragraph Command 12 Units to be used 13 12. Command. — a. When under infantry command . — Due to the difficulty of maintaining long communications that might be interrupted, as well as the fact that when the necessity for the use of single anti-tank artillery pieces exists, the supporting artillery is busiest in coordinating its efforts as such, it is burdensome (if not impossible) for any artillery headquarters to attempt to control promptly these widely separated single pieces in their purely local tasks. In the general case, in the zone defense and position defense , — 16 — anti-tank guns properly fall within the tactical command of infantry front line commanders, as attached artillery. b. When under artillery command . — Since, in the de- ployed defense , flexibility of maneuver is demanded, and the opportunities become fewer for safely installing single pieces in concealed positions well forward from which they may surely act with surprise effect, and as time for detailed arrangements will be much more limited, artillery anti- tank defense must be undertaken generally by entire batteries. These usually will be the most advanced batteries in each battalion, and, in addition to attacking other suitable targets of opportunity, will function as a part of the supporting artillery. 13. Units to be Used. — a . Single units only to be dis- rupted. — In order to allow batteries to be utilized in the man- ner for which they are essentially organized, and to prevent each of several batteries from suffering a severe loss in fighting efficiency, complete units should be broken up to supply the guns needed for anti-tank defense, except when the contrary action is justified by a very extensive front. If four pieces are needed, a single battery only should suffer disruption ; if five or six pieces are needed, then in addition to one battery, an additional section or platoon is detailed from another battery. Such part of the disrupted battery as must be kept withdrawn to the rear — limbers, caissons, animals, etc. — should be kept as a whole for administration and supply. b. Use of the platoon. — When a choice of position is per- mitted, anti-tank pieces are emplaced singly and cooperate in their fire tactics by the use of cross fire on their targets. Concealment, which enables surprise effect to be obtained, can be far more readily obtained for a single piece than a platoon. Hence, the use of a platoon as a tactical unit is unusual for anti-tank defense. Y'f+wj 35 ZA \Av\3fc t ' v.\ 1 A$ -I >5 S- "■s I V \ ' | * Vj S INTRODUCTION The Line Class Course in Tactics and Technique of Ar- tillery is covered in Volume I of this subject. It is intended to present a sufficient knowledge of artillery units and their employment to prepare for the solution of problems in com- bined arms — especially of units not larger than a division. The main part of the text therefore treats of the division artillery. There has been included also an introductory, elemen- tary study of Corps and Army Artillery, Coast and Harbor Defense, Submarine Mine Defense, Railway Artillery, and Anti-aircraft Defense, sufficient in its scope to disclose the relation of division artillery to that of the corps and army, and to prepare for the more advanced course in the General Staff School. These latter subjects are taken up in greater detail in Volume II, which is used as a text-book for the Staff School. The fable of Contents presents a detailed synopsis of the subject matter covered. A preliminary study of the Glossary of Artillery Terms” will aid in an understanding oi the application of the principles taught. In the preparation of the text, an attempt has been made to present only so much of purely technical artillery matters as has appeared necessary in order to appreciate the powers and limitations of Field Artillery and to ap- proach the study of the combined arms with a proper conception of the role played by this arm in supporting in- fantry under battle conditions. The intimate relation that must exist between com- manders of assaulting battalions of infantry and support- ing battalions of artillery has been especially brought out. Ihe effort is made, also, to impress upon the reader the necessity for a consideration of the element of time in em- placing and moving artillery units, and in necessary pre- paration of firing data, which, together with definite assign- ment of missions, accurate designation of targets, and full knowledge of troop movements, is so essential to success. It is believed that the necessity for combined effort and unity of artillery control has been clearly presented; like- 57 1099 INTRODUCTION wise the necessity for a flexibility of fire direction that permits quick concentrations by all’ available units so as to promote the success of the whole, while recognizing the routine and direct support of infantry assaulting units by the artillery closely linked therewith. The principles of organization in depth, the defense of successive battle posi- tions, the mechanics of artillery support, and forward dis- placement in successful attacks, are clearly set forth. The text presents the necessity for infantry-artillery teamwork; demonstrates the appropriate command of sup- porting artillery units; and makes clear the situation that calls for the assignment of accompanying batteries and accompanying guns, and for the attachment of artillery units to subordinate infantry commands. Much use has been made of the appropriate lessons of The World War. The teachings also recognize recent de- velopments made in all arms and auxiliary units, and reveal a keen conception of their mode of employment in modern war. H. A. Drum, Assistant Commandant. Approved ; H. E. ELY, Commandant. IV Glossary of Artillery Terms Section I. — General Section II. — Kinds of Fire Paragraphs 1-16 16-37 Section I General 1. Artillery. (a) Attached Artillery. — Artillery temporarily de- tached from its organic command and placed tem- porarily under the orders of another commander. (b) Accompanying Batteries. — Batteries attached nor- mally to infantry regiments. They assist the in- fantry when it is out of touch with the supporting artillery. (c) Accompanying Guns. — Guns attached to smaller infantry units — generally assault battalions — for use as emergency weapons. (d) Accompanying Artillery. — A term used to include accompanying batteries and accompanying guns. Accompanying artillery is under command of the infantry unit commander and advances in con- junction with the unit to which attached. (e) Supporting Artillery. — Artillery supporting units of other arms, while retained under its usual ar- tillery command. 2. Batteries. (a) Decoy Batteries. — Batteries (often dummy) in- stalled to draw hostile attention, thus keeping the enemy from firing at batteries whose position it is desired not to disclose. (b) Silent Batteries. — Batteries, generally in defense, prepared to fire but kept silent, to prevent dis- closing their positions until a general attack or other emergency requires their use. GLOSSARY OF ARTILLERY TERMS 3. Columns. (a) Double Section Column. — Carriages in double column — caissons (of gun sections) abreast of pieces. Usual formation for going into action. (b) Section Column. — Carriages in single column — normally each piece followed by its caisson. Usual march formation. 4. Defilade. (a) Defilade. — Concealment from all points within the enemy’s position. (b) Dismounted Defilade. — A position in which a dis- mounted man — standing — can just see the hostile position over the mask. (c) Mounted Defilade. — A position in which a mounted man can just see the hostile position over the mask. (d) Flash Defilade. — A position in which the flash of the guns will be defiladed. Requires ordinarily about 4 yards’ defilade for 75-mm. guns. 5. Echelons. (a) Echelons ( Artillery ). — Subdivisions of artillery units made for the purpose of placing to the rear such elements as are not required at firing posi- tions or with forward groups. A rear echelon will generally contain administrative personnel and spare men, horses and materiel. When artil- lery is in action, limbers of firing batteries, main- tenance sections of firing batteries, battalion com- bat trains, regimental supply trains and frequently caisson bodies of gun sections will all be posted in rear. Some of these units may be posted together, or all have separate positions. (b) Echelonment in Depth. — The disposition of artil- lery batteries or other firing units in depth with respect to the enemy. 6. Field of Fire. — The terrain which can be covered by the fire of an artillery unit from a given position. 7. Front of Battery. — The front occupied by a battery in firing position. Normally a battery of light or VI GLOSSARY OF ARTILLERY TERMS medium field artillery occupies about 100 yards’ frontage. This may be considerably decreased, and at times will be considerably increased. 8. Guns. (a) Anti-Tank Guns. — Guns detached from batteries and pushed forward for individual use against tanks. (b) Roving Guns. — Guns detached usually from regu- larly installed batteries and given the mission of firing from many different positions, so as to con- ceal regular positions and mislead the enemy as to artillery strength. 9. In Action. — A rtillery in position and firing, or about to fire. 10. Laying. (a) Direct Laying. — Guns laid by directing line of sight on actual target. (b) Indirect Laying. — Guns laid by directing line of sight on an auxiliary reference point (aiming point) with proper deflection to bring the guns on the target. 11. Lifting Fire. — The operation of shifting fire from one target to another at greater range. 12. Limbered and Unlimbered. — A battery is limbered when the trails of the guns (or howitzers) and cais- sons are attached to their respective limbers; un- limbered when the trails are free of the limbers and lowered to the ground. A battery is limbered preparatory to movement ; unlimbered preparatory to firing. 13. March Order. — An artillery command given when a battery is in firing position, preliminary to its being limbered. Sights are removed, covers re- placed, and guns and carriages generally prepared to be limbered. 14. Positions. (a) Alternate Positions. — Positions prepared for use if those originally occupied become untenable. vii GLOSSARY OF ARTILLERY TERMS (b) Gas Positions . — Alternate positions for use when the original positions are rendered untenable by gas. (c) Positions in Readiness. — Units limbered and ready to move or to go into action. Held (normally un- der cover) awaiting orders. (d) Positions in Observation. — Units in position and prepared for action, but do not open fire without orders from higher authority, except in case of emergency when communication is impracticable. (e) Position for Immediate Action. — Units in position from which fire will be delivered without further orders from higher authority. 15. Rocket Posts. — Stations from which rockets are fired. Such signals are often used to call down prear- ranged defensive fires. Section II Kinds of Fire 16. Accompanying Fire. — Artillery fire supporting the in- fantry in its advance. 17. Artillery Preparation. — Fire delivered prior to, and in preparation for an attack. 18. Barrage. (a) Barrage . — A barrier or curtain of fire. (b) Rolling Barrage. — A barrage that moves at a pre- determined rate. When used, it generally pre- cedes infantry advancing in an attack. (c) Standing Barrage. — A barrage that does not move. It is laid on a line the enemy is expected to at- tempt to pass. (d) Normal Barrage . — A standing barrage laid by an artillery unit in immediate defense of the sector which it supports. (e) Eventual Barrage . — A standing barrage laid by an artillery unit either to assist in the defense of Vlll GLOSSARY OF ARTILLERY TERMS an adjacent sector, or as a possible defense of its own sector when the normal barrage is not ap- plicable. (f) Box Barrage. — A continuous standing barrage, put down so as to cover the rear and flanks of an area to prevent the escape of an enemy, or to protect the operation of a friendly force. 19. Bombardment. — A term sometimes used to describe artillery preparation. 20. Concentration. — Fire by one or more units (often several firing simultaneously) upon a designated position or a given area. 21. Covering Fire. — A term at times applied to any ac- companying fire. More properly limited to fires upon flanks, and upon strong points for neutrali- zation to permit their being passed. 22. Counter Battery. — Fire directed upon hostile artillery in position. 23. Counter Battery Officer.— An officer designated to regulate, supervise and control the counter bat- tery work of the command. 24. Counter Offensive Preparation. — Fire placed on as- sembly points, lines of departure, and routes lead- ing thereto from which it is believed the enemy is about to launch an attack. The purpose of this fire is to break up a hostile attack before it can be ' launched. 25. Destruction Fire. — Fire intended to cause the destruc r tion of the (material) target attacked. 26. Enfilading Fire. — Fire whose general direction is par- allel to and intended to rake the hostile lines or works. 27. Fire for Adjustment. — Fire for the purpose of cor- recting initial firing data before passing to fire for effect. 28. Fire for Effect. — Fire for the purpose of accomplish- ing a designated mission. Normally, adjustment is continued throughout fire for effect. IX GLOSSARY OF ARTILLERY TERMS 29. Fire for Registration. — Fire for adjustment, using as a target some prominent terrain feature in or near the enemy’s known positions, so that later a prompt and effective fire for effect can be placed on any target in that vicinity. 30. Harassing Fire. — F ire delivered for the purpose of an- noying the enemy, causing casualties, and lower- ing the enemy morale. 31. Interdiction Fire. — F ire delivered on established or probable lines of hostile advance, particularly on vital points thereof, for the purpose of preventing movements of troops or supplies. Its most com- mon application is by enfilade fire on roads and rail- roads available to the enemy. 32. Neutralizing Fire. — Fire whose object is the prohibit- ing of all hostile activity within the area covered. 33. Observed Fire. — F ire in which the firing data are com- puted for initial firing, after which corrections are based on observation of fire. 34. Organized Fire. — Prearranged fire which may be placed mechanically, without regard to observation. However, when practicable it should be observed. 35. Progressive Fire. — Any accompanying fire which pre- cedes the infantry advance. 30. Progressive Concentrations. — Accompanying fire which precedes the infantry advance by lifting from target to target, but without the regularity of the rolling barrage. 37. Surprise Fire. — Fire of opportunity ; fire delivered with great rapidity upon transient targets. TACTICS AND TECHNIQUE, ARTILLERY (Line School Course) Volume 1 1921-1922 CONTENTS VOLUME I Introduction. Glossary of Artillery Terms. Chapter I . — Organization and Command of Artillery Units. Paragraphs General Discussion v 1 Classes of Artillery 2 Artillery Organization 3 Artillery Command 4 Artillery Units 5 Section 6 Platoon 7 Battery 8 Battalion 9 Regiment 10 Brigade 11 Groupment 12 Day of Fire 13 Transport 14 Pack Artillery 15 Motorized Artillery 16 Portee Artillery 17 Railway Artillery 18 Distribution of Artillery Personnel 19 Small Arms Equipment 20 Division Artillery, Infantry Division 21 Division Artillery, Cavalry Division 22 Artillery of Larger Units 23 Chapter II. — Artillery Weapons and Ammunition. Section I, Weapons. Classification, General 1 Light Artillery 2 Medium Artillery 3 Heavy Artillery 4 Section II , Ammunition. Ammunition, Defined, Kinds 5 Kinds Used by Various Types of Weapons 6 The Charge 7 The Primer 8 The Charge in Several Parts 9 Form and Type of Projectiles 10 Projectiles Classified 11 Shrapnel 12 Effect of Shell and Shrapnel Compared 13 Kinds of Projectiles, Standard for Certain Weapons 14 The Future of Shrapnel 15 Fuses, Defined and Classified : 16 Percussion Fuses 17 Time Fuses 18 Safety Precautions 19' Proportions of Various Types of Projectiles in Ammunition Vehicles 20 Effect of Individual Projectiles 21 Selection of Ammunition for a Given Mission 22 Effect of Artillery Fire Sometimes Overestimated 23 Ammunition Required for Given Missions 24 xii TABLE OF CONTENTS Paragraphs Chapter III . — Artillery Chemical Shells. Introduction 1 Gases Used in American Shells 2 Calibers of Chemical Shell 3 Gas Shell 4 Smoke Shell 5 Fuses for Gas Shell 6 Adjustment of Fire j. 7 Ammunition Consumption 8 Smoke Screens 9 Conditions Affecting the Use of Chemical Shell 10 Artillery Gas Tactics 11 Gas in the Offensive 12 Gas in the Defensive 13 Smoke Tactics 14 Defense Against Gas 15 Transportation and Storage 16 Markings of Chemical Shell 17 Chapter IV . — Artillery Ammunition Supply. General 1 Agencies of Ammunition Supply 2 Use of Ammunition Supply Agencies 3 Normal Loads Held in Reserve 4 Accumulations of Ammunition 5 Kinds and Amounts of Ammunition Carried 6 Replenishment of Ammunition 7 Ammunition for Corps Artillery Attached to a Division 8 The Artillery Brigade Munitions Officer 9 Munitions Reports 10 Small Arms Ammunition 11 System Shown by Graphics 12 Chapter V . — Artillery Firing. Section I, General. Recent Developments 1 Old Methods Essential _ 2 Duty of Artillery 3 Section II, Preparation of Fire. Definition 4 Mechanism of Laying 5 Kinds of Laying 0 Laying for Direction 7 Finding the Deflection 8 Angular Measurements 9 Systems of Deflection Graduation 10 Map and Compass Laying 11 Deflection Difference 12 Laying for Elevation 13 Finding the Site 14 Finding the Range 15 Finding the Elevation 16 Time Fire 17 Summary of Firing Data 18 Refinements of the Preparation of Fire 19 Ballistic Corrections 20 Conclusions as to Preparation of Fire 21 xiii TABLE OF CONTENTS Paragraphs Section 111, Firing Over Obstacles. Clearing the Crest 22 Reaching a Reverse Slope 23 Section IV, Ballistics. Defined 24 Trajectory 25 Nomenclature of Trajectory 26 Drift 27 Jump 28 Effect of Muzzle Velocity and Elevation on Range 29 Rigidity of the Trajectory 30 Atmospheric Conditions : 31 Section V, Dispersion, Probability. General 32 Defined 33 General Effects of Dispersion 34 Nature of Dispersion 35 Dispersion on Sloping Ground 36 Safety of Friendly Troops Due to Dispersion 37 Probable Error 38 Probability 39 Section VI, Firing. Subdivisions of Firing 40 Observation 41 Methods of Adjustment 42 Adjustment by Measured Deviations 43 Adjustment by Bracketing 44 Adjustment of Time Fire . 45 Method of Fire During Adjustment 46 Fire for Effect 47 Registration 48 Barrages 49 Section VII, Aerial Observation. General 50 Balloon Observation 51 Airplane Observation , 52 Chapter VI . — Selection of Positions. Section I, Reconnaissance. Reconnaissance for Positions 1 Reconnaissance for Information 2 The General Selection of Artillery Positions.- 3 The Progression of Artillery Reconnaissance 4 Additional Reconnaissance Required 5 Conveyances for Reconnaissance 6 Instructions to Artillery Units During a Reconnaissance 7 Time Available for Artillery Reconnaissance 8 Transmission of Information During a Reconnaissance 9 Reconnaissance by Heavy Artillery 10 Section II, Selection of Positions. Tactical Considerations in the Selection of Artillery Positions 11 Tactical Classifications of Artillery Positions 12 Selection of Battery Positions 13 Considerations Affecting the Selection of Battery Positions. 14 Considerations of Range 15 The Field of Fire and Dead Spaces 16 xiv TABLE OF CONTENTS Paragraphs Considerations of Communications in the Selection of a Bat- tery Position 17 Consideration of Observation in the Selection of Battery Po- sitions ^ 18 Concealment 19 Facility of Movement 20 Favorable Conditions for Resupply of Ammunition 21 Cover for Limbers or Gun Tractors 22 Gun Emplacements 23 Interference with the Operations of Other Troops 24 Security of a Battery Position 25 Protection of Guns and Personnel • 26 Chapter VII . — Artillery Communications. Section 1, General. Means of Communication 1 General Characteristics 2 Dependence Upon Other Systems 3 Communication Between Artillery Units of the Same Com- mand 4 Communication With Troops Supported by Artillery 5 Supervision and Coordination 6 Section II, Telephone. Telephone Communications, Past and Present 7 Telephone Equipment for Field Artillery 8 Laying Telephone Wire 9 Selection of Wire 10 Battery Communications 1 11 Battalion Telephone Communications 12 Regimental Telephone Communications 13 Brigade Telephone Communications 14 Section III, Radio. Radio Communication Dependent upon Available Equipment 15 Communication Between Airplanes and Artillery 16 Radio Communication Between Artillery Headquarters 17 Radio Communication with Infantry 18 Section IV, Communication with Advancing Infantry. Communication with Advancing Infantry 19 Section V, Pyrotechnics. Pyrotechnics in an Advance 20 Pyrotechnics in Defense 21 Section VI, Training. Training of Artillery Signal Personnel 22 Chapter VIII . — General Principles Governing the Tactical Em- ployment of Artillery. Basis of Tactical Use 1 Characteristics 2 Limitations 3 Effect of Limitations 4 Purpose of Field Artillery 5 The Infantry Artillery Team 6 ArtiUery Tactics Defined 7 No Independent Artillery Role 3 Utility of Study * 0 xv TABLE OF CONTENTS Paragraphs Information the Artilleryman Must Have 10 Battle Units 11 Primary Mission — Division Artillery 12 Organization for Combat 13 Disposition of Attached Artillery 14 Disposition for Command 15 Decisions re Artillery Employment 16 The Division Order 17 Chapter IX. — The Tactical and Technical Employment of the Battery. The Battery a Technical Unit 1 Light Battery the Standard 2 Composition and Subdivision 3 The Battery Headquarters 4 The Battery Detail 6 Battery Reconnaissance (see also Chap. VI.) 6 Orders of the Battery Commander 7 The Firing Battery 8 Battery Combat Train 9 Ammunition 10 Batteries Employed Independently (see also Chap. XIII.) — 11 Change of Position 12 Communications 13 Administration and Supply 14 Conduct of Fire 15 Observation of Fire 16 Map Firing 17 Chapter X. — Tactical Employment of the Battalion. Light, Medium and Heavy Artillery Battalions 1 General Functions of the Battalion 2 General Functions of the Battalion Commander 3 Keeping the Battalion Intact 4 Formations of Battalion 5 Reconnaissance (see also Chap. VI.) 6 Selection of Positions (see also Chap. VI.) 7 Security 8 Communication 9 Observation 10 Ammunition Supply 11 Changes of Position 12 Supporting the Infantry 13 Battalion Orders 14 Conditions Affecting the Efficacy of Battalion Employment- 15 Offensive Employment 16 Defensive Employment 17 Disposition of the Batteries 18 Disposition of Combat Train (see Chap. VI.) 19 Provisional Battalion 20 Chapter XI. — Tactical Employment of the Regiment and Brigade. Section 1, The Regiment. Composition 1 General Functions 2 The Rear Echelon 3 The Regiment on the March — 4 Disposition of the Regiment in Action 5 Sectors of Fire 6 xvi TABLE OF CONTENTS Paragraphs Troops to be Supported 7 Enemy Batteries — 8 Movements from Position to Position 1 9 Regimental Headquarters 10 The Service Battery 11 Reconnaissance (see also Chap. VI.) 12 Communications (see also Chapter VII.) 13 Observation 14 Regimental Orders 15 Section II, The Artillery Brigade. Composition 16 Headquarters of a Field Artillery Brigade 17 General Functions 18 Tactical Employment of the Brigade 19 Sectors of Fire 20 Regimental Principles Applicable to Brigade 21 Summary of Battle Functions 22 Chapter XII. — Artillery on the March and its Entry into Action. Disposition on the March 1 Subdivision of Artillery on the March 2 Artillery Headquarters on the March 3 Conduct of Marches 4 Rates of March 5 Distances 6 Reconnaissance on the March 7 Communications 8 Entry into Action from the March 9 Chapter XIII. — Accompanying Batteries and Accompanying Guns. Defined 1 General Purpose 2 Historical 3 When Used 4 Duration of Mission, Orders 5 Command of Accompanying Artillery 6 Missions 7 Units from Which Accompanying Artillery Should be De- tailed 9 Moral Effect of Attached Artillery 10 Attached Artillery Drawing Fire 'll Equipment of Accompanying Artillery 12 Suitability of 75-mm. Guns 13 Necessity for Combined Training 14 Chapter XIV. — Division Artillery in the Offensive. Section I , General. General Kinds of Fire Support Tactical Employment of Fire Preparation - Destruction Observation Neutralization During the Attack The Rolling Barrage Successive Concentrations XVII TABLE OF CONTENTS Paragraphs Other Concentrations 11 Counter Battery ~ 12 Interdiction ~~ ~~ 13 Fire on Transient Targets 14 Positions IIII_III 15 Forward Displacement 16 Missions ”11 17 Organization of Command 18 Limbers, Combat Trains and Field Trains 19 Section II, Meeting Engagement. Position on the March 20 Advance Guard Artillery 21 Plan of Attack 22 The Development 3 23 Counter Battery 24 Approach March and Deployment 25 Advance to the First Firing Position II 26 The Attack Proper ” 27 The Pursuit IIIIII 28 Section III, Attack of Enemy Deployed for Defense. The Situation 29 Artillery Action 30 Section IV, Attack of a Prepared Position. Situation 31 Preliminary Action I I 32 Artillery Preparation ~ 33 The Attack Hill 34 Section V, Attack of a Defensive Zone. Situation 35 Artillery Action t I 36 Continuing the Support I I 37 Chapter XV . — Division Artillery in the Defensive. Section I, General. General Duties and Principles 1 Methods of Support 2 Tactical Employment of Artillery Fire 3 The Defensive Barrage 4 Counter Preparations 5 Defensive Concentrations 6 Deployment 7 Missions 8 Organization of the Command , 9 Section II, Defense in a Meeting Engagement. Situation 10 Action of the Artillery 11 Section III, Deployed Defense — Defensive Position. Deployed Defense — Defensive Position 12 Section IV, Defensive Zones. Artillery Positions 13 Section V, Withdrawal and Retreat. General Discussion 14 Fires 15 xviii TABLE OF CONTENTS Paragraphs Chapter XVI . — Artillery Combat Orders. Artillery Provisions of Army and Corps Orders 1 Artillery Subparagraph of a Division Field Order 2 Field Order of the Field Artillery Brigade 3 Artillery Annex to the Division Order — : 4 Orders of Regiments and Subordinate Units 5 Use of Maps and Charts 6 Chapter XVII . — Corps and Army Artillery. Introduction 1 Unity of Fire Direction in the Combat Unit 2 The Division Artillery 3 Corps Artillery 4 Summary of Corps Artillery Missions 5 Organic Artillery of the Corps 6 Front Covered Determines Assignment » 7 Mission Determines Location of Guns 8 General Character of Corps Types of Weapons 9 Army and Corps Field Orders 10 Army Artillery ^ 11 New Army Artillery Organization 12 Organization into Brigades — Training, etc. 13 Railway Artillery 14 General Scheme of Artillery Support and Assignment 15 Percentage of Guns— Division and Army 16 Chapter XVIII . — The Artillery Information Service. Origin, Development and Characteristics 1 Organization 2 Sources of Information ! 3 Information from the Air Service 4 Army and Corps Artillery Information Service 5 Functions of Division Artillery Information Service 6 Regimental Artillery Information Service 7 Battalion and Battery AIS 8 Operations under Varying Conditions 9 Chapter XIX. — Anti-Aircraft Service. General 1 Function of Coast Artillery Corps 2 Materiel and Missions 3 Tactical Employment 4 Organization 5 Technique 6 Chapter XX . — Coast and Harbor Defense. Section 1, Introduction 1 Section II, General Description 2 Modifications Since World War 3 Section III, Forces Employed. Forces Employed for Defense — 4 Naval Forces 5 Land Forces - 6 Missions : 7 Armament 8 Organization 9 Projectiles 10 xix TABLE OF CONTENTS Paragraphs Trend of Development 11 Mounts and Emplacements 12 Fire Control System , 13 Security and Information 1 14 Section IV, Forms of Attack 15 Characteristics of Naval Targets 16 Coast Artillery Defense 17 Artillery Position 18 Concentration of Fire 19 Kinds of Fire 20 Tactics of Fire 21 Night Attacks 22 Heavy Artillery Available for Coast Defense 23 Section V, Submarine Mines in Relation to Coast Defense. Definition 24 Operated by Army 25 Classification , 26 Location of Mines 27 Components of Mine Defense 28 Passageways and Sailing Directions 29 Possible Future Development 30 Appendix. Pages Range tables of 75-mm. gun and 155-mm. howitzer 304-307 Charts illustrating artillery fire 308-314 The protective barrage. Box Barrage. Organization of rolling barrage. Counter preparation. Ground pattern of shell bursts. Illustrative Terrain Exercises and Map Problems 315-367 xx I — 1-2 CHAPTER I Organization and Command of Artillery Units Paragraphs General Discussion 1 Classes of Artillery 2 Artillery Organization 3 Artillery Command 4 Artillery Units 5 Section 6 Platoon 7 Battery 8 Battalion 9 Regiment 10 Brigade 11 Groupment 12 Day of Fire 13 Transport 14 Pack Artillery 15 Motorized Artillery 16 Portee Artillery 17 Railway Artillery 18 Distribution of Artillery Personnel 19 Small Arms Equipment 20 Division Artillery, Infantry Division 21 Division Artillery, Cavalry Division 22 Artillery of Larger Units 23 1. General Discussion. — A division, when acting alone, usually has corps artillery attached, and, when acting as a part of a corps, may have other artillery attached, and normally is supported by corps artillery and possibly by GHQ reserve artillery. Hence, this volume includes the necessary consideration of other than division artillery. Volume II treats of corps, army and GHQ reserve artillery. 2. Classes of Artillery. — From the standpoint of materiel, field artillery is classified as light, medium, and heavy. In our service all light artillery is now (1921) equipped with 75-mm. guns. The 155-mm. howitzer and the 4.7-inch gun are classed as medium artillery. All field artillery of heavier caliber is classed as heavy artillery. 1-3-5 2 TACTICS AND TECHNIQUE— ARTILLERY 3. Artillery Organization. — (a) Fro;m the stand- point of organization, the artillery, with the armies in the field, is divided into : Division Artillery. Corps Artillery. Army Artillery. General Headquarters Reserve Artillery. (b) Each of these is separate and distinct from the other. The term “Army Artillery” or “Corps Artillery” does not include the organic artillery of subordinate units. When referring to all the artillery in an army or a corps use the expression “the artillery with — ^-Army” or “the artillery with Corps.” (c) The scheme of organization of the artillery with a typical army is shown diagrammatically in Plate II. A numerical summary of important units is given in Plate III. The corps and army data are to be regarded as a basis of organization only, as the number of divisions in a corps, and corps in an army, is not fixed, especially during active operation. 4. Artillery Command.— There is ho chain of ar- tillery command between an army and a division. Com- mand of the artillery is exercised by the commander of the unit to which it belongs or is attached. Control by higher commanders is exercised through the normal chain of com- mand. The senior artillery commander on duty with a unit, unless otherwise specially directed, commands all the artillery belonging to the unit or attached thereto. The army artillery commander is the advisor of the army com- mander on artillery matters. Likewise, the division ar- tillery commander is the advisor of the division commander. The chief of the corps artillery headquarters performs this duty for the corps commander. 5. Artillery Units. — The basis of artillery organiza- tion is the efficient employment of the pieces in action. The units and their commanders, in general terms, are as fol- lows: 1-5-8 ORGANIZATION AND COMMAND 3 Unit Commander Section Sergeant. Platoon Lieutenant. Battery Captain. Battalion Major. Regiment Colonel. Brigade Brigadier General. Groupment is explained later. 6. Section. — (a) A gun section consists of a gun and its caisson, manned, horsed (or provided with motor power) and equipped. A caisson section consists of two caissons similarly provided. A section ordinarily operates as part of a platoon, or battery, but in special cases may be de- tached to act alone. (b) The 75-mm. gun section, in addition to the gun, has a gun limber, carrying 18 rounds of ammunition, a cais- son limber, carrying 36 rounds, and a caisson body carry- ing 70 rounds. The total for a section is 124 rounds. The caisson limber and caisson body together form what is commonly called a caisson. A 75-mm. caisson section has two such caissons, and carries a total of 2 (36 plus 70), or 212 rounds. (c) The 155-mm. howitzer limber does not carry am- munition; it is simply a support for the trail. The 155- mm. howitzer section includes two caisson bodies, each carry- ing 14 rounds, or a total of 28 rounds for the caisson. The caisson section includes two such “caissons/’ or a total of 56 rounds for the section. 7. Platoon. — A platoon, which consists of two sec- tions, is simply a convenient command subdivision of the battery. In rare cases, however, it may be detached to act alone. 8. Battery. — (a) The battery is primarily a firing unit. It is the smallest administrative unit. Tactically, it operates ordinarily as part of a battalion, but in small commands, or in special cases, may act alone. (b) In theory a battery should consist of the greatest- number of pieces whose fire can be effectively conducted technically by one person. The practical application of this theory has given rise to much discussion. Prior to the introduction by France in 1898 of the modern long recoil 1—8 4 TACTICS AND TECHNIQUE— ARTILLERY field gun, the 6-gun battery was practically universal. After its introduction, with its increased rate of fire and ammuni- tion consumption, France concluded, after exhaustive ex- periments, that the 6-gun battery was too large and reduced it to four guns. Other nations, upon adopting a modern gun, adopted various battery' organizations. Many, in- cluding the United States, followed the lead of France; others, notably England and Germany, adhered to the 6- gun battery. Early in The World War, however, Germany reorganized on the basis of the 4-gun battery. (c) A small battery is extravagant in officers and headquarters personnel. A consideration of man power alone favors the large battery. The small battery has the advantage of ease of handling and mobility. The technical difficulties in the conduct of fire are magnified in the large battery, and great skill is required to develop the full power in all situations. Modern artillery consumes much am- munition, but the supply can be provided for either a 4-gun battery or a 6-gun battery. Ammunition supply, therefore, is not a serious consideration in deciding between the two types of battery organization. (d) The United States, probably chiefly influenced by the question of ease of technical control, adopted the 4-gun battery for all artillery, except trench artillery and some of the most powerful types of railway artillery. The battery has been lightened by taking the ammunition carrying element of the former combat train out of the battery. It has been formed into a battalion combat train, organized as a separate unit. (e) A battery is organized thus: Battery headquarters. Firing battery. Maintenance section. (1) The battery headquarters is organized for command, reconnaissance, preparation of firing data, and information. (2) The firing battery, the unit which occupies a firing position, includes four gun sections and one caisson section. As already explained, a 75-mm. gun section carries 124 rounds of ammunition, and a caisson section 212 rounds. So the battery has 124 plus 212 or 177 rounds per piece. Similarly, a 155-mm. howitzer battery has 28 plus 56 or 42 rounds per piece. (3) The maintenance section provides means for the re- placement and repair of materiel. It includes a rolling kitchen, a water cart, a ration cart, and the maintenance personnel of the battery. ORGANIZATION AND COMMAND 5 (f) The light artillery battery is shown diagrammati- cally in Plate I. Other battery organizations are generally similar to it. The battery officers are distributed ordinarily as follows: 1 captain, battery commander. 1 first lieutenant, battery executive. 1 second lieutenant, assistant to the executive. 1 second lieutenant, reconnaissance officer. 9. Battalion. — (a) The battalion is primarily a tac- tical unit, and is also a convenient subdivision for general command. It practically never is used as a fire unit. In the large artillery commands it may function tactically as a part of a regiment or groupment. (b) The battalion consists of: Headquarters and headquarters battery. Battalion combat train. 3 batteries in the division light artillery, portee artillery and horse artillery (separate battalion), or 2 batteries in medium and heavy battalions. (c) The number of batteries in a battalion is prin- cipally a question of convenience and effectiveness of tac- tical employment. For example, a corps 155-mm. regiment attached to a division may employ a battalion as support to each infantry brigade and one as general support to the division. The three battalions in corps and GHQ reserve regiments lend themselves readily for employment in widely separated positions and missions. In foreign armies, bat- talions are more usually of three batteries for both light and heavy artillery. The British battalion, called a bri- gade, is habitually of four batteries of six pieces each. (d) The battalion combat train is in effect an ammu- nition battery. It consists of: Train headquarters. Two or three platoons, of three sections each. The number of platoons is the same as the number of batteries in the battalion. For the 75-mm. gun, caisson sections are used; for the 155-mm. howitzer, truck sections are used. The amount of ammunition carried is given in the chap- ter on ammunition supply. Maintenance section. If occasion demands, one platoon can be detached read- ily for service with a detached battery. 6 TACTICS AND TECHNIQUE— ARTILLERY 10. Regiment. — (a) The regiment is both an ad- ministrative and a tactical unit. It consists of : Regimental headquarters and headquarters battery. Service battery. Two 3-battery battalions, or three 2-battery battalions. Attached medical personnel and equipment, and attached chaplains. (b) Regimental headquarters and headquarters bat- tery consist of the personnel, the animals, and the equipment necessary for the command and tactical employment of the regiment, and for the maintenance of regimental head- quarters and the headquarters battery itself. (c) The service battery is a unit for the supply and baggage transport of the regiment. It also includes the regimental band and the personnel for its own mess and maintenance. It is organized so that a detached battery or battalion can be accompanied by a proportionate quota of the service battery, which then functions as a battery or battalion field train. 11. Brigade. — T he brigade is principally a tactical unit. It consists of : Headquarters and headquarters battery. 2 (or more) regiments. Ammunition train. 12. Groupment.' — In the tactical handling of large masses of artillery it is frequently inexpedient to preserve the tactical unity of the larger artillery units, such as bri- gades and regiments. On the other hand, it is necessary that the command be decentralized and localized to secure the greatest degree of efficiency. This is accomplished by the formation, for particular operations, of temporary, im- provised, tactical units, called “groupments.” The units, batteries, battalions, and regiments, are conveniently grouped, depending on location and mission rather than on permanent organization or caliber. Available commanders and staffs of permanent organizations are utilizedTor group- ment commanders and staffs. 13. Day of Fire. — The day of fire is an arbitrary unit of measure of ammunition and is taken as follows, based on our experience in The World War: ORGANIZATION' AND COMMAND ;L — 13-19 7 Weapon Day of . Fire Rounds Per Piece 75-mm. gun 155-mm. howitzer 155-mm. gun 240-mm. howitzer 300 150 100 60 The new organization provides a total of about 1^ days of fire with the guns, combat train, and ammunition trains, for division and corps artillery. 14. Transport. — In the matter of transport, artillery is classed as horse-drawn, pack, motorized, portee, and railway. Only the 75-mm. gun of the division artillery is horse-drawn, the teams being 6-horse. It should be noted, however, that these guns constitute nearly half of all the artillery with a typical army. 15. Pack Artillery. — The 1920 organization provides one regiment of pack or mountain artillery for the GHQ artillery reserve, and certain other units for use in the for- eign possessions. In these units, the transport is the pack mule. Pack artillery has been used for many years in our service, but was not used in the AEF. 16. Motorized Artillery. — The motorized artillery now in service includes the 155-mm. howitzer, the 155-mm. gun, and the 240-mm. howitzer. These weapons are drawn by tractors. 17. Portee Artillery. — The portee (or truck car- ried) artillery includes some of the regiments of 75-mm. guns of the GHQ reserve artillery. 18. Railway Artillery. — The railway artillery in- cludes a variety of guns and mortars ranging in caliber from 8 to 16 inches, inclusive. New types are being de- veloped. The 1920 organization contemplates only 12-inch and 16-inch guns. 19. Distribution of Artillery Personnel. — A rela- tively small proportion of the personnel of artillery is re- quired for the actual service of the pieces in action. A relatively large proportion is required on other essential duties, such as staffs, details for instruments, communica- tions, information, liaison, ammunition, supply and trans- portation. For example, the personnel of a light regiment and battery may be classified approximately as follows : I — 19-21 8 TACTICS AND TECHNIQUE— ARTILLERY Regiment Battery No. % No. % Service of pieces 288 19 48 34 Transport _ 461 31 42 30 Instruments _ 44 3 5 4 Information _ _ 40 3 3 1.5 Communication _ Supply, maintenance, ad- ministration (includes 146 9 13 9.5 supply of ammunition) 401 27 23 17 Command, reserve, and others 127 8 6 4 1507 100 140 100 20. Small Arms Equipment. — Artillery combatant units at present have small arms equipment substantially as follows: (a) Division Artillery: All individuals armed with the pistol. 8 automatic rifles per battery, and service battery, or 56 per regiment. No rifles. 2 machine guns per battery and service battery; 3 per bat- talion combat train, or 20 per regiment. 8 automatic rifles and two machine guns per ammunition com- pany of brigade ammunition train. Automatic rifles, only for the battalion combat train of horse artillery battalions. (b) Corps, Army and GHQ Reserve Artillery: Small arms equipment follows the same general scheme : rail- road regiments are equipped (partially) with rifles. 21. Division Artillery. — Infantry Division. — (a) The division artillery is the quota included in the tabular organization of the division. Its primary function is in- fantry support. (b) The following principles underlie the division ar- tillery organization: (1) That it is essential that a quota of artillery be perman- ently assigned to a division. The object is to secure, by constant association and working together, close cooperation between the infantry and artillery. Without this cooperation the full fighting efficiency of the division cannot be developed. The soundness of this principle was demonstrated repeatedly in our operations in The World War. (2) That the quantity and kind of division artillery be such as is necessary and practicable in moving situations, considering difficulties of supply, maintenance, and roads. Too much will encumber the division; too little will increase the infantry casual- ties and diminish the effectiveness of the division as a whole. In stabilized situations, the division artillery, when necessary, 1 - 21-22 ORGANIZATION AND COMMAND 9 can be readily augmented by attaching units from divisions out of line, from corps artillery, or from a general reserve. (3) That the types included in the division artillery pro- vide a large volume of projectiles effective against personnel, animals, and material; and a certain quantity of projectiles effec- tive against field works, at least hastily constructed ones. The trajectories to be such that, to a reasonable extent, the fire will not be masked by ordinary accidents of the terrain. However, great destruction of sheltered personnel is not contemplated with division artillery; it seeks rather to neutralize by keeping down the enemy’s fire, thus enabling the infantry to succeed by virtue of the superiority of its fire and its movement. (c) The division artillery consists of a brigade com- posed of a brigade headquarters and headquarters battery, two regiments of light artillery, and an ammunition train. (1) The brigade headquarters has two light motor cars, two reconnaissance cars, and four motorcycles with side cars. It has also 53 riding horses as mounts for individuals, which are used in reconnaissance and general service when motors are not practicable. Transport for supplies and equipment is horsed. (2) The light artillery regiments are essentially horsed, most of the vehicles being 6-horse. One driver handles a pair of horses. Cannoneers of animal-drawn artillery normally walk, but during rapid movements, or on other necessary occasions, they ride on limbers and caissons. The general organization of these regiments has already been given. (3) The brigade ammunition train consists of: Train headquarters. One transport company. One ammunition company. The transport company has a wagon section of 27 wagons, 25 of which are available for transportation of ammunition, and a truck section of 27 trucks. Twenty-five of the trucks are in- tended for artillery ammunition, one for small arms ammuni- tion, and one for gasoline in drums. The organization is based on a carrying capacity of one-half day of fire of 75-mm. ammu- nition, and the necessary pistol, anti-aircraft machine gun, and automatic rifle ammunition. Trucks can carry 200 rounds and wagons 100 rounds of 75-mm. ammunition. One wagon and one truck are available for the required small arms ammunition. The transport company is split- into motorized and animal-drawn sections; this in order that the ammunition train may be able to function under any circumstances in which the other trains of the division, and the transport of the regiments of the bri- gade, can function. The ammunition company provides the labor incident to the supply, handling, and delivery of ammunition. 22. Division Artillery. — Cavalry Division. — The ar- tillery quota of a cavalry division is one separate battalion of horse artillery; that is, light artillery made more mobile by mounting the cannoneers on individual mounts. The bat- talion has three batteries, a battalion headquarters and headquarters battery, and a combat train. The organiza- I-t— 22-23 TACTICS AND TECHNIQUE— ARTILLERY 10 tion is almost identical with the light artillery battalion, ex- cept that additional horses are provided to mount the can- noneers and a few other additional men. A service platoon takes the place of a service battery. It is a part of the battalion combat train. 23. Artillery of Larger Units. — (a) While this vol- ume deals primarily with division artillery, it is deemed advisable to consider briefly the artillery of units larger than a division. (b) Corps Artillery .* — Corps artillery consists of a corps artillery headquarters, and a corps artillery brigade. The former headquarters is distinct from the headquarters of the latter. (1) Corps artillery headquarters is a section of the corps staff It is made necessary by the large amount of technical detail connected with the handling of large masses of artillery. Its functions are to coordinate the operations of the corps ar- tillery brigade and the division brigades, and to control the opera- tions of such artillery reinforcements as may be assigned to the corps^y £ or p S artillery brigade is entirely motorized and consists of: Brigade headquarters. x 3 regiments, 155-mm. howitzers (24 howitzers each), (i.e., 1 regiment per division in normal corps); 1 regiment, 155-mm. guns (24 guns) ; 1 observation (flash) battalion; 1 ammunition train. . ,. (3) A detailed description of the material and organization is given in Vol. II. As a regiment of 155-mm. howitzers is often attached to a division a brief description of this unit is appro- Priat fa) A regiment of 155-mm. howitzers is armed as indi- cated, and has the same general organization as that of a 75-mm. gun regiment. It has three 2-battery battalions. The transport is entirely motor, 5-ton tractors being used for the firing batteries, trucks for battalion combat tram ammunition transport; trucks for field train, and trailers for reel cart, water cart, rolling kitchen, and anti-aircraft machine guns. A 5-ton tractor draws a howitzer and limber, about 8927 lbs., or two caisson bodies, about 8000 lbs. On account of lack of seating space on the caissons and tractors, ammunition trucks are provided solely for transporting per- ‘sonncl. Ho) The formal service of the piece requires a gunner and 5 cannoneers as in a light battery. The number of cannoneers provided, therefore, seems excessive, but in real- ity is not so. The manual labor involved in serving a heavy piece (the 155-mm. howitzer projectile weighs 100 pounds) is so considerable that experience has shown that it is neces- sary to provide two shifts of cannoneers. 1—23 ORGANIZATION AND COMMAND 11 (c) Army Artillery organically consists of only the army artillery headquarters and ammunition train. In op- erations, artillery units are assigned to an army from the General Headquarters Artillery Reserve for use as army artillery, or for reassignment to corps and independent di- visions. (d) GHQ Reserve Artillery . — The object of the GHQ artillery reserve is to provide a pool of artillery, particularly of heavy and special types, which can be drawn upon by the combatant units as needed. This relieves tactical units of many of the routine burdens of administration, training, and upkeep of these units, and, at the same time, provides artillery for distribution according to the requirements. The reserve, as such, has no tactical functions. (1) The projected pro rata of GHQ Reserve Artillery for one Army is: Light artillery 1 Brigade of Brigade Headquarters; 3 regiments 75-mm. guns (portee) ; total 72 guns. 3 regiments 75-mm. guns (motorized) ; total, 72 guns. Medium and Heavy Artillery 1 Brigade of Brigade Headquarters; 2 regiments 155-mm. guns (motorized) ; total 48 guns. 2 regiments 240-mm. howitzers (motorized) ; total 48 howitzers. 1 regiment 6-inch guns (motorized) ; total, 24 guns. (2) The GHQ Reserve Artillery for 6 Armies is, 6 times the amount for one army and also: 1 Regiment trench mortars; 24 mortars. 1 Regiment 12-inch guns (railroad) ; 12 guns. 1 Regiment 16-inch guns (railroad) ; 12 guns. Sound ranging service of Headquarters. 10 sound ranging companies. (3) In addition to the above, the GHQ Reserve Artillery is used in time of war to collect all artillery, of any and all cali- bers, that may be available, or become so during the war. BATTERY OF LIGHT ARTILLERY 12 TACTICS AND TECHNIQUE— ARTILLERY t* X 1 1 < M o g 5 £ Ah Q Z O c3 O CO C T3 c C4 NUMERICAL SUMMARY OF ARTILLERY ORGANIZATIONS To face page 12 Unit Table of Org No. . Personnel Pieces Animals Animal drawn Vehicles Total Remarks Officers (Com. & Warrant) Enlisted Men Total Motors Motor drawn Brig Div Arty 31 W 169 Com 4 War 3227 3400 48 3432 423 49 1 473 Brig Corps Arty 402 Com 6 War 8196 8694 96 1436 495 1931 Brig Mdm and Hv Arty (GHQ Res) 541 W 438 Com 5 War 10228 10671 120 1818 588 2406 Brig Anti-aircraft Arty (GHQ Res) 520 W 426 Com 6 War 8949 9381 72 1152 132 1284 288 machine guns anti-aircraft Brig Anti-aircraft Arty (Army) 220 W 219 Com 3 War 4512 4734 36 582 66 648 144 machine guns anti-aircraft Hq Div Arty Brig 32 W 12 Com 2 War 75 89 87 8 4 12 Hq Corps Arty Brig (Mot.) 132 W 12 Com 2 War 76 89 11 111 Hq Mdm & Hv Arty Brig GHQ Res (Mot) 552 W 12 Com 75 87 12 12 3 Regt 75-mm. Gun Div 33 W 75 Com 1 War 1495 1671 24 1607 193 5 198 Regt 75-mm. Gun Portee 253 W 69 Com 849 918 24 112 16 128 Sep Bn 75-mm. Gun Horse Arty Cav Div 436 W 30 Com 760 790 12 1091 96 96 Regt 75-mm. j ^ 533 W 74 Com 1 War 1520 ll 695 24 2039 28 28 . 855 Packs Regt 155-mm. How 133 W 84 Com 1 War 1694 lj 779 24 300 140 440 1 Regt 155-mm. or 6-in.-Gun 143 W 83 Com 1 War 1811 1 895 24 295 62 357 1 Regt 240-mm. How 76 Com 1 War 2180 2 257 24 417 187 604 Regt anti-aircraft Artillery 120 W 69 Com 1 War 1479 549 12 189 22 211 j 48 machine guns anti-aircraft Regt 12-in. or 16-in. Gun 553 W 75 Com 1 War 1349 425 12 70 TO 95 railway cars, 4 locomotives Regt Trench Mortar 543 W 64 Com 1 War 1465 i >30 36 113 22 135 Div Arty Am Tn 56 W 7 Com 162 169 131 29 35 1 65 Eorps Arty Am Tn 156 W 37 Com 1021 1 058 209 9 218 Army Arty Am Tn . 256 W 28 Com 518 5 46 193 6 199 Observation (Flash) Bn-corps 163 W 18 Com 207 225 21 4 25 | Sound ranging Service, GHQ, Reserve 549 W 68 Com 891 >59 76 20 96 (A) Motorcycles not included. PLAT! 1 III ■ rn THE LIBRARY OF THE EW flF MJJSSMS Corps Artillery To face page 12 ARTILLERY WITH A TYPICAL ARMY— 3 CORPS— 9 DIVISIONS ARTILLERY WITH I CORPS | Begt ; t jlI ARTILLERY WITH II CORPS ARTILLERY WITH III CORPS CORPS ARTILLERY BRIGADE An ti-air craft CORPS ARTILLERY BRIGADE CORPS ARTILLERY BRIGADE (Separate regt not a part of corps arty proper) | Army Am Tn| (6 transport Cos) Anti-aircraft 1 bn 76 G 1 bn MG’s 1 SL Co L bn 76 G L bn MG’s L SL Co 1 Brigade 3 Regts (motorized) 3 Regts (Portee) 1 Brigade (Motorized 166 mm G Regt 156 mm G Regt 240 mm H Regt 240 mm H Regt 6-in G Regt II— 1 CHAPTER II Artillery Weapons and Ammunition Paragraphs Section" I. — Weapons 1- 4 Section II. — Ammunition 5-24 Section I Weapons Classification, General 1 Light Artillery 2 Medium Artillery 3 Heavy Artillery 4 1. Classification, General. — (a) Artillery may be classed broadly as follows : (1) Field Artillery, that which is designed primarily to accompany an army in the field. There are the following sub- divisions : (a) Light Artillery , exemplified by the 75-mm. gun. A howitzer of the same mobilitiy would be included in this class, for example, the projected 105-mm. howitzer. Light artillery is primarily for infantry support. (b) Medium Artillery. — Guns of caliber between that of the light field gun and the field gun of about 6-inch caliber. It is exemplified by the 4.7 gun. The medium howitzer should be of the same mobility and of about 6-inch caliber. The 155-mm. howitzer is an example of this type. (c) Horse Artillery , similar to the light artillery, but with greater mobility, all cannoneers being individually mounted. Intended for work with cavalry. (d) Pack Artillery , intended primarily to replace light artillery in difficult terrain which is unsuitable for wheeled vehicles. (e) Heavy Artillery, which includes all types of wheeled or caterpillar artillery heavier than medium artillery. (f) Trench Artillery, a special type of mortars, of short range, useful principally in stabilized or similar situations. (2) Railway Artillery, that in which the mount is spe- cially constructed for firing and transport on railroad tracks. In some types, the piece also can be fired from fixed or semi- fixed platforms. This type is an important element of coast de- 13 II— 1-2 14 TACTICS AND TECHNIQUE— ARTILLERY fense, but it also is capable of being used with the armies in the field under some conditions; hence its special classification. (3) Coast Artillery, that designed primarily for coast de- fense, mostly on fixed mounts. (4) Anti-Aircraft Artillery, a special type for anti-air- craft defense. It may be employed with the armies in the field, for the defense of localities, or as an adjunct of coast defenses. It is not a part of the field artillery. (b) More elaborate classifications than the foregoing frequently are made; for example, the most powerful guns in some cases are distinguished by the term high power guns; the term super-gun also is used. (c) For the more important characteristics of the prin- cipal service types of field, railway, and anti-aircraft artil- lery, and field artillery under development, see the tables following this chapter. Only the field artillery is considered here. 2. Light Artillery. — (a) While the individual piece of light artillery is not powerful as compared with the heav- ier types, the light artillery is easily the dominant type. In point of numbers, it constitutes about one-half of the artil- lery with the armies in the field ; in addition, it has greater all-round usefulness than any other type. There are three types of light artillery at present available for service, the French, the British, and the Amer- ican model of 1916; all are 75-mm. guns. The French type predominates, and was used exclusively in France. The British type was adopted to hasten the equipment of our artillery units in The World War. The American Model of 1916 is of American design and manufacture. Its develop- ment was well under way before our entry into The World War; it probably would have been our service type had it been possible to attain quantity production with sufficient rapidity. All three of these types use the same ammuni- tion. (b) The 75~mm. French Gun , Model of 1897 . — This is the service type of the French Army, introduced by them in 1898 ; it was the forerunner of all modern field artillery, and is today one of the most efficient weapons in existence. Of those on hand in our service, a portion were purchased from the French and a portion were manufactured in this country. II— 2 ARTILLERY WEAPONS AND AMMUNITION 15 Tiie weight of the gun and carriage in the firing posi- tion is 2657 pounds; the weight behind the team, including a loaded gun limber (18 rounds), but without cannoneers on the limber, is 4181 pounds. The maximum permissible ele- vation of the gun on the carriage with the latter on level ground, is 19 degrees ; depression, 10 degrees. The permis- sible traverse of the gun on the carriage is 6 degrees, 3 de- grees on each side of the center. A shield of limited extent is provided ; the thickness is 4 millimeters (.16 inches) . The recoil system is of the type known as hydro-pneumatic, the recoil being checked by a hydraulic brake (oil), and the counter-recoil being effected by compressed air. The length of the recoil is 44.9 inches. The carriage embodies the so- called independent line of sight system of laying the gun for elevation. The sight is an optical one, but without mag- nification or the panoramic feature which is standard in our service. v (c) The 75-mm. British Gun, Model of 1917. (1) This is the service type of the British Army, except 4hat the British use a caliber of 3.3 inehes (18-pounder). Those in our service are of American manufacture. The fact that, at the time of our entry into The World War, this type was in produc- tion in this country for the British government led to its adop- tion with modified caliber for our service. It is considered a very satisfactory weapon. (2) The weight of the gun and carriage in the firing posi- tion is 2,945 pounds; the weight behind the team, including a loaded gun limber (18 rounds), but without cannoneers, is 4,469 pounds. The maximum permissible elevation of the gun on the carriage is 16 degrees; depression, 5 degrees. The permissible traverse of the gun on the carriage is 8 degrees, 4 degrees on ? each side of the center. A shield is provided. The recoil is checked by a hydraulic buffer; the gun is returned to battery by a spring column, which is compressed in recoil. The length of recoil is 49 inches. An unusual feature of the carriage is that the gun is mounted under the cradle, instead of above it, as is the common practice. The carriage embodies the independent line of sight system of laying for elevation. The sight is the standard pan- oramic type of our service. (d) The 75-mm. American Gun, Model of 1916. (1) This gun is quite similar to the Deport (French) gun, which was the; first one produced of this type. The Italian field gun is also of the Deport type. (2) The weight of the gun and carriage in the firing posi- ' tion is 3,045 pounds; the weight behind the team, including the loaded limber, is 4,569 pounds. It has the so-called split trail. Instead of the usual single or box trail, the trail is in two wings secured to the axie inside of each wheel. The trail spades lock 16 TACTICS AND TECHNIQUE — ARTILLERY together in limbering for transport, but, for firing, the trails are spread apart so as to pfermit the gun to recoil between them through a traverse of 22 degrees 30 minutes on each side of the center. The maximum permissible elevation of the gun on the carriage is 53 degrees, the maximum depression is 7 degrees. The recoil system is of the hydraulic-spring type. The length of re- coil is varied automatically by the mechanism, from 46 inches at zero elevation to 18 inches at extreme elevation. This variable recoil is necessary to insure stability of the carriage in firing at low elevations and to prevent the breech of the gun from striking the ground when firing at high elevations. The carriage has the independent line of sight, and is equipped with a shield. (e) New Types . — The approved artillery development project of the War Department includes a 75-mm. gun and a 105-mm. howitzer, of new type. They are still in the ex- perimental stage. In the split trail type, the same carriage will be used for both weapons. It is expected that the gun will attain a range of 15,000 yards with a 15-pound projec- tile and the howitzer a range of 12,000 yards with a 33- pound projectile. (f) Horse Artillery . — In our service, the horse artil- lery always has used the same materiel as the light artil- lery, i.e., the gun of 3-inch or 75-mm. caliber. (g) Pack Artillery . — While this is not a part of divi- sion artillery, it is attached to divisions when the situation demands its use. The present materiel of the pack artillery is an American-made copy of that purchased some twenty years ago from the Vickers-Maxim Company, of England. Though called a gun, the weapon is a howitzer strictly speak- ing. It is of 75-mm. caliber, and fires a shell or shrapnel weighing 12J pounds to an extreme range of 5000 yards. The carriage, though very rugged and serviceable, is not of modern type in that it is not stable in firing and permits no traverse of the piece on the carriage. In firing, the car- riage recoils on the ground, but this is reduced to some ex- tent by the piece recoiling on the carriage, about 14 inches. This type of carriage is known as the short-recoil. The piece can be elevated on the carriage to a maximum of 27 degrees and depressed to 10 degrees. The carriage has been modified to receive the service panoramic sight, which permits the use of indirect laying. The materiel is designed for transport by pack mule, and for this purpose separates into four loads: the piece II— 2-4 ARTILLERY WEAPONS AND AMMUNITION 17 235 pounds, the cradle, 186 pounds; the wheels and axle, 178 pounds; and the trail, 231 pounds. The weight of the howitzer in the firing position is 830 pounds. The materiel can be unpacked and assembled for firing, or the reverse, in less than one minute. One round per piece per minute may be taken as a fair maximum rate of aimed fire. This rate is determined by the operations of relaying and not by the wear of the bore. 3. Medium Artillery. — (a) These weapons belong to the corps artillery. However, they are at times attached to divisions, hence a brief description is given here. (b) The 7 -inch Gun, Model of 1906. (1) This type was in service for a number oi years before The World War; it is of American design and manufacture. It is not included in the present organization. (2) The weight of the gun and carriage in the firing posi- tion is 8,068 pounds; the weight behind the tractor, including a limber, simply to support the trail, is 9,818 pounds. The maxi- mum permissible elevation of the gun on the carriage is 15 de- grees; depression, 5 degrees. The traverse on the carriage is 4 degrees on each side of the center. There is a shield. The recoil system is hydraulic-spring, the recoil of the gun on the carriage being 70 inches. The carriage is equipped with the panoramic sight, but has not the independent line of sight. (c) The 155-mm. Howitzer, Model of 1918 ( Schneider ) . (1) This weapon was produced originally by the French firm of Schneider and Company, and is a service type of the French Army. It was adopted for our service after our entry into The World War; those now on hand are partly of French and partly of American manufacture. The type was used ex- tensively in our operations, and proved very satisfactory. During the war, the power of the howitzer was increased over that con- templated originally by increasing the powder charge. The use of this augmented charge stresses the materiel severely, and if used too extensively will cause serious damage. (2) The weight of the howitzer in the firing position is 7,600 pounds; the weight behind the tractor, including a limber, simply to support the trail, is 8,927 pounds. The maximum per- missible elevation of the howitzer on the carriage is 42 degrees; depression, zero. The traverse on the carriage is 3 degrees on either side of the center. There is a shield. The recoil system is hydro-pneumatic, the length of recoil being 51 inches. The lay- ing system does not include the independent line of sight. 4. Heavy Artillery. — Characteristics of these wea- pons is given in the tables following this chapter. They are described in detail in Volume II of this text. II— 5 Section II Ammunition Paragraphs Ammunition, Defined, Kinds Kinds Used by Various Types of Weapons The Charge The Primer The Charge in Several Parts Form and Type of Projectiles Projectiles Classified Shrapnel Effect of Shell and Shrapnel Compared Kinds of Projectiles, Standard for Certain Weapons The Future of Shrapnel Fuses, Defined and Classified Percussion Fuses Time Fuses Safety Precautions Proportions of Various Types of Projectiles in Ammuni- tion Vehicles Effect of Individual Projectiles Selection of Ammunition for a Given Mission ____________ Effect of Artillery Fire Sometimes Overestimated Ammunition Required for Given Missions 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 21 22 23 24 5. Ammunition, Defined, Kinds. — A round of am- munition consists of one projectile and the necessary pro- pelling charge of powder, the primer, igniter and containers. Ammunition is classed as fixed, semi-fixed, and separate- loading. In fixed ammunition, the round is handled and loaded in the piece as a unit, in the same manner as small arms ammunition. The cartridge case, usually of brass, con- tains the primer, igniter, and propelling charge ; the projec- tile is forced into the mouth of the cartridge case, and leaves it only when the round is fired. Semi-fixed ammunition is the same as fixed ammunition, except that the projectile is removable from the cartridge case by hand, usually for the purpose of varying the charge. Sometimes a lock is provided for securing the projectile in the cartridge case. The round is loaded in the piece as a unit. In separate load- ing ammunition, the projectile and the charge are separate and are loaded in the piece separately. The propelling charge, primer, and igniter may be contained in a cartridge 18 II— 5-8 AMMUNITION 19 case as for fixed and semi-fixed ammunition ; or the igniter and propelling charge may be contained in a bag of com- bustible, cloth, which is consumed in firing. In the latter case, the primer is inserted in the breech mechanism separ- ately. Separate loading is used for heavy ammunition; in the case of worn pieces, it gives greater accuracy, as the projectiles can be well seated by ramming. The cartridge case for separate loading protects the charge and makes loading easier and more rapid ; it is costly however, and for the large calibers, heavy. 6. Kinds Used by Various Types of Weapons. — The light artillery of all nations uses fixed ammunition. There are many examples of pieces using separate loading ammu- nition, among them being our 155-mm. howitzer and all larger calibers. The 75-mm. pack howitzer and 105-mm. howitzer, now being developed for our service, as well as the 4.7-inch gun, probably will use semi-fixed ammunition. 7. The Charge. — The propelling charge is of smoke- less powder with grains so designed as to present a gra- dually increasing burning surface and of a size appropriate to the caliber and length of the bore. The igniter is one or more small packets of black powder suitably distributed in the charge, to insure a thorough and reliable ignition of the propellant. For small calibers, such as the 75-mm. gun, the necessary igniting charge is included as a part of the primer. 8. The Primer. — T he primer (Figure 1) is a device resembling a small arms cartridge placed at the base of the Figure 1. — 21-grain Percussion Primer, Mark IIA. II— 8-9 20 TACTICS AND TECHNIQUE— ARTILLERY charge to furnish the initial ignition when the piece is fired. The percussion primer, used in field artillery, consists essen- tially of a percussion cap and a small amount of compressed black powder. The cap is struck by the firing pin in firing. Electric primers are used in some seacoast pieces. 9. The Charge in Several Parts. — For certain pieces, the charge is made up in several parts. (Figure 2.) By the removal of one or more parts, the charge can be var- ied. The advantage of this is two-fold. First, a sufficient charge can be used to give the desired range and no more; this saves the bore, since the greater the charge the greater the wear of the bore. Second, a reduced charge, if sufficient to give the range desired, gives a greater angle of fall than a greater charge ; this facilitates reaching behind accidents of the terrain. The practice of using variable charges was extended greatly during the war. While it has the disadvantage of complicating the am- munition, this is considered to be more than outweighed by the gain in ballistic properties in most cases. In fact, the use of variable charges for the light field gun is being con- sidered. The French use reduced charge ammunition in their light field gun to give a more curved trajectory, but this is fixed ammunition and is distinct from the normal type. In the variable charges used up to the present, the II — 9-10 AMMUNITION 21 component parts are not of uniform size and weight. This presents some disadvantages in manufacture and in utiliz- ing the parts removed. Studies and experiments are now being made in our service with what are known as aliquot part charges. These are variable charges in which the component parts are identical and interchangeable. Parts not used in one charge are available to make up others; moreover, there is less liability to error in making up charges. 10. Form and Type of Projectiles. — The forms and types of ogival projectiles (Figures 3 and 4) were the sub- 3A5C CCVtt- / — ADAPTER 5HELL Figure 3. — 155-mm. Forged Steel Shell ject of extensive study and experiment before the war, but, nevertheless, the changes during the war were numerous and marked ; and since the war, research has been taken up with renewed impetus. To quote from the report of the so-called Caliber Board in this connection: “There are in- vestigations under way by the Ordnance Department cov- ering this entire subject and the Board recommends that these be continued. It is to be expected that this subject 11 - 10-12 22 TACTICS AND TECHNIQUE— ARTILLERY will require extended investigation and is one which can only be adequately handled by a continuing technical body.” The development of the form of the projectile consists principally in lengthening the ogive thus giving the projec- tile a long sharp point, and in tapering the base in rear of the rotating band, called “boat-tailing.” The projectile modified in this manner sometimes is called a stream-line projectile, and closely resembles the modern small arms bullet. The effect of these modifications of form is to give a considerable increase in range. 11. Projectiles Classified. — Projectiles are classed as shell and shrapnel , depending on their action on bursting. The shell is a forged steel or semi-steel projectile, filled with high explosive, which is detonated by a fuse carried in the point of the projectile (in the base for armor-piercing shell). The effect is obtained by the projectile being broken up by the action of the bursting charge into fragments projected at very high velocity. The endeavor is to make the bursting charge as large as possible. This is limited by considera- tions of weight and size from the ballistic standpoint (high explosive has a lower specific gravity than steel), and by the fact that the projectile must have sufficient strength to withstand the shock of firing. A projectile specially de- signed for a howitzer cannot be fired in a gun of like cali- ber, as it would break up under the firing stresses incident to the higher velocity of the gun. Forged steel is superior to semi-steel, as the fragments are larger and more destruc- tive, and the shell walls can be made thinner. Semi-steel, a special form of cast iron, gives a shell with satisfactory fragmentation, and it is cheaper and better adapted than forged steel in quantity production. 12. Shrapnel. — Shrapnel (Figure 5) consists essen- tially of a steel envelope as for shell, a base charge of black powder, a large number of balls embedded in a smoke-pro- ducing matrix, and a combination time and percussion fuse. The fuse is set so as to burst the projectile in air just before it strikes. The percussion element of the fuse is merely an alternative to insure the burst of the shrapnel in case the time element of the fuse does not function as intended. Shrapnel are not employed deliberately with the idea of AMMUNITION 23 Fuse nose piece (tezs) — 7=lv ASSEMBLE D 7Jme_ fuse nngs (brass ) — SHRAPNEL Fuse cover {fin ) Resin Shrapnel bof/s Powder lube (brass ) Naptha lene. Gun codon Diaphragm (steel ) 'Shrapnel or shell head Obiuraior (straw board ). Cartridge case (drawn brass ) Pnmer (brass) (screw machine product ) —Bourre/et - Steel shell bod y (forged & machined ) Resin Black powder Cop per band or rotating band. Smokeless powder Hrac/vc/zan H/y'-s/on Con Ser//ori rr£s?«'-£s/ J ?%. yj ames r jTLfprj t-9»/ Or* ** < Z)rau/r7 by /ar/£*>1 [ J>i~i Figure 5. — Shrapnel. II — 12-15 24 TACTICS AND TECHNIQUE— ARTILLERY their bursting on impact, as their effect in this case is much reduced. The action of the base charge of black powder is to push out the head of the projectile and to propel the balls with increased velocity; the cylindrical portion of the case is not ruptured. The balls are intended to be individ- ually effective against personnel or animals, when the shrap- nel bursts in air at the proper height. 13. Effect of Shell and Shrapnel Compared. — The effect of shell, when burst at or above ground, is principally lateral ; the effect of shrapnel is entirely to the front. Shrap- nel is effective over a larger area than shell of the same caliber. The relative moral effect of shell and shrapnel is a matter of dispute. A projectile was developed by the Germans before the war, called unit projectile or high ex- plosive shrapnel, which was intended to combine the shell and shrapnel. It resembled a shrapnel, but the bullets were embedded in high explosive instead of a non-explosive ma- trix. When burst in air, the projectile functioned as a shrap- nel, the matrix not being detonated. When burst on per- cussion, the matrix was detonated, and the entire projectile ruptured in the manner of a shell. The projectile was some- what complicated, and was not thoroughly efficient either as a shell or a shrapnel; the type disappeared early in the war, and may be considered as definitely abandoned. 14. Kinds of Projectiles Standard for Certain Weapons. — The shell is a standard type of projectile for all types and calibers of artillery. The shrapnel is standard for the lighter calibers, such as the 75-mm. gun, the 4.7 inch gun and the 105-mm. howitzer (new). Shrapnel is sup- plied for the present 155-mm. howitzer, but has been aban- doned for the new weapons of this type. 15. The Future of Shrapnel. — The future of the shrapnel is not assured, even though it survived the war. The shrapnel is relatively ineffective in howitzers, and even in guns at the longer ranges, because the high angle of fall contracts very much the ground pattern of shrapnel. In guns firing at long range, the dispersion of the fuse be- comes great and makes the effect unreliable; in addition, there is difficulty in making a time fuse of a time capacity adequate for long range firing. The shrapnel and its fuse II — 15-17 AMMUNITION 25 are more difficult and costly to manufacture than the shell. The firing of shrapnel is limited practically to the daytime when visibility and other conditions permit the bursts to be observed. The technical conduct of shrapnel fire is more difficult than that of shell ; in fact it is questionable whether the hastily trained war officer can be expected to handle shrapnel effectively. While a well placed shrapnel is more effective against animate targets in the open than shell, dis- persion causes a certain proportion of shrapnel fired to burst on graze with little effect. On the other hand, the new shell fuses give bursts effective almost entirely above the ground, making their action not unlike that of shrapnel. The shell is independent of fuse dispersion and can be used effectively without observation. 16. Fuses, Defined and Classified. — The fuse is the element of the projectile which causes it to burst at the end of its flight. Fuses may be classed as point or base, according to the position of the fuse in the projectile; point fuses now are used exclusively for field artillery projectiles. The more usual classification is based on the action of the fuse: percussion fuses, which function when the projectile strikes; time fuses, which function any desired time after the projectile leaves the bore; and combination fuses, which have both percussion and time elements, the percus- sion element functioning automatically unless the time ele- ment acts beforehand. Percussion fuses are widely used for all calibers of field artillery; time fuses are used only in anti-aircraft artillery when firing over friendly territory ; combination fuses are used for all shrapnel, and in some cases with shell. 17. Percussion Fuses. — Percussion fuses are of vari- ous types, depending on the particular characteristics of design, and on their speed of action after the projectile strikes. The most rapid action is in the case of the super- quick or long fuse (French I.A.L. or Mark III) (Figure 6), which is intended to burst the projectile slightly before it strikes the ground. This is effected by means of a long fuse projecting ahead of the point of the projectile. The instan- taneous fuse (Figure 7) bursts the projectile just as it 26 TACTICS AND TECHNIQUE— ARTILLERY Figure 6. — Point detonating fuse (long), Mark III Figure 7. — Point detonating fuse (short) Mark IV 11 - 17-18 AMMUNITION 27 strikes, the action being slightly later than in the case of the super-quick fuse. A still slower action is obtained with the short delay fuse. This action results in the projectile burying itself slightly before bursting ; or if there is a rico- chet, the burst is in air just above the ground. Ricochet ac- tion is obtained only with guns, under certain conditions of terrain and at ranges generally not exceeding 4500 yards. The long delay fuse is used to obtain the maximum penetra- tion and mining effect with heavy projectiles. The long fuse lessens the range and accuracy slightly. It is unreliable in its action where the angle of impact is small. The present effort in our service is to reduce the num- ber of percussion fuses to two for each caliber, one a super- quick and the other short delay. It is possible that these two actions can be combined in a single fuse, capable of be- ing set beforehand for the particular action desired. 18. Time Fuses. — T ime fuses (Figure 8) are con- structed with a time element consisting of a train of powder Figure 8. — Forty-five-second Combination Fuse, Mark I which burns progressively. The fuse is set so that it will act after this powder train has burned a distance corres- ponding to the time desired. Considerable progress has been made in the development of mechanical time fuses , which are based on the clockwork principle. The fuses are practicable, and are particularly useful in firing to great al- titudes, where the rarified air would affect the burning of a time train. They are delicate and costly, and difficult to produce in quantities in time of war ; their principal applica- tion doubtless will be in anti-aircraft artillery. 11-19-21 28 TACTICS AND TECHNIQUE— ARTILLERY 19. Safety Precautions. — Shells habitually are issued and transported without fuses, because of the sensitiveness of the latter; the fuse is inserted by hand just before load- ing. This also permits selection of the fuse used. Shrapnel always is issued fused and ready to fire. Fuses are provided with various safety devices, to protect against premature action either during transport or during the passage of the projectile through the bore. Safety devices for transport only are positive devices which are removed before the pro- jectile is loaded in the piece; the bore safety devices also protect during transport. Accidents in handling ammuni- tion are now very rare. Making the fuse bore-safe is diffi- cult, and it may be said that no shell fuse now existing is entirely satisfactory in this respect. The mechanisms for this purpose fall in two categories; those utilizing the in- ertia of certain moving parts to arm the fuse, that is, make it capable of functioning, by the shock of discharge and not before; and those utilizing the rotation of the projectile to arm the fuse by means of the centrifugal action of certain moving parts. Long and painstaking effort has been de- voted to this feature of fuses, but it continues to be a source of danger to gun crews and has resulted in many fatal acci- dents. Detonations in the bore, usually due to the fuse, generally are shrouded in mystery, and the exact cause rarely is determined. A slight obstruction in the bore causes a sudden retardation of the projectile and is ordin- arily sufficient to cause the fuse to act, if it is armed, in the same manner as when the projectile strikes. An ir- regularity in the copper rotating band or a foreign sub- stance adhering thereto is apt to cause explosion in the bore, hence care is needed. 20. Proportions of Various Types of Projectiles in Ammunition Vehicles. — The proportions of the different types of projectiles to be carried in the artillery ammunition and combat trains has not been prescribed by the War De- partment; and even if a normal apportionment were pre- scribed, it doubtless would be varied in actual operations to meet conditions. 21. Effect of Individual Projectiles. — (a) When a shrapnel bursts, the balls are projected forward in a coni- 11—21 AMMUNITION 29 cal sheaf. The angle at the projectile or the vertex of the cone varies with the velocity of the projectile at the instant of burst, being greater for long ranges than for short ones ; it may be taken roughly as 15 degrees. The area on the ground covered by the balls depends on the height of the burst above the ground and on the angle of fall. Shrap- nel balls lose their velocity very rapidly, their maximum effective range being 300 or 400 yards. The balls are not distributed uniformly over the ground pattern, being denser for the elements nearest the piece. The effective pat- tern of the 75-mm. shrapnel when burst in air at a suitable height may be taken roughly as 150 to 100 yards in range, varying with the range, and 25 yards laterally. The effect of shrapnel bursting on graze is problematical; if there is a richochet, the effect may be comparable to that of an air burst; but ordinarily the balls are merely scattered on the ground with a very local and mild effect. (b) A bursting shell has three distinct sheafs of frag- ments, the lateral sheaf, the ogival or forward sheaf, and the base or rear sheaf. The lateral sheaf is the most impor- tant and is the only one counted on for effect. The shell fragments have a very high initial velocity, said to be be- tween 3000 and 5000 feet per second ; but the jagged irregu- lar fragments have little ballistic efficiency and lose their velocity almost immediately. Small fragments do not fly generally more than about 30 yards, although occasional large fragments may fly several hundred yards. (c) The following table, from French sources, gives the area covered effectively by 75-mm. and 155-mm. shells, fused so as to burst at or slightly above the surface of the ground. Type of ehell Area effective covered In range Laterally yards 1 ards Effective radius of largest frag - 75-mm. high explosive steel shell 5 155-mm. high explosive steel shell 8 155-mm. high explosive semi-steel shell__ 15 ment. Yards 15 70 70 150 500 200 (d) In time shell fire, the most effective height of burst is taken as 20 yards vertically above the target. If the shell is fused so as to burst after penetrating the ground 11-21-23 30 TACTICS AND TECHNIQUE— ARTILLERY partially or wholly, the surface effect diminishes or disap- pears. Such effects may be desired, however, for the de- struction of dugouts, casemates or other material objects of great resistance. (e) Incidental effects of the detonation of shells are concussion and gas poisoning. The former may be serious in case of large shells. The latter occurs in confined spaces such as casemates or dugouts. 22. Selection of Ammunition for a Given Mission. — (a) Against personnel or animals in the open, the fol- lowing ammunition may be used effectively ; time shrapnel, which under favorable conditions is the most effective ; time shell; percussion shell with a super-quick fuse; percussion shell with a delay fuse when ricochets will be obtained. When the personnel is sheltered in open trenches, time shrapnel will only neutralize the personnel, unless the trench can be enfiladed. Time or percussion shell fired from a direction perpendicular to the trench is effective, but a very accurate adjustment of fire is necessary. Shell is less effective than shrapnel for enfilading a trench. (b) When penetration is necessary, shell with delay fuse is used. (c) In service, the fuses available often restrict the choice materially. 23. Effect of Artillery Fire Sometimes Over- estimated. — (a) It is a common tendency to overestimate the material effect of artillery fire. This may give rise to the following difficulties: (1) The artillery may be assigned missions so extensive that they cannot be executed effectively; (2) The time allotted for the execution of missions may be inadequate; or (3) The ammunition expenditure involved in the assigned missions may be so great as to make their execution impracticable in a given situation. (b) The individual projectile is a powerful agency of destruction near its point of fall, but it is difficult to place this point of fall at the particular point whose destruction is sought, due to imperfect preparation of fire, lack of ob- servation, and dispersion. IX — 24 AMMUNITION 31 ,24. Ammunition Required for Given Missions. — The following data, principally from French sources, are given to permit calculations to be made as to the ammunition con- sumption for various missions assigned the artillery. If a rate of fire is assumed, it is possible to arrive at the time necessary. These tables are general guides only, as it is impossible to specify the exact number of rounds necessary to accomplish any given destruction. (a) Destruction of a Hostile Battery: By the 75-mm. gun 500 to 800 rounds. By the 155-mm. howitzer 300 to 400 rounds. By the 155-mm. gun 400 to 600 rounds. In each case, it is assumed that the hostile battery is not so well protected as to prevent its successful attack by the weapon in question. (b) Wire Cutting : By the 75-mm. gun, a breach 25 yards wide in a band of wire 15 to 20 yards deep, when fired by one battery, at mid-range 600 to 800 rounds. At long range 1000 to 1200 rounds. By the 155-mm. howitzer, same breach 300 to 400 rounds. (c) Destruction of Trenches : 75-mm. gun, not effective, except to a certain extent when the trench can be enfiladed. By the 155-mm. howitzer, for each point se- lected for destruction 80 to 100 rounds. From the foregoing figures, it is evident that only in exceptional cases is it possible to undertake destructions in the strict sense of the term. (d) Violent Bombardment. — A violent bombardment of an area sometimes is advisable to produce casualties among personnel distributed irregularly over it but more or less without cover. The fire should be as rapid as possible, and should be based on the following expenditure of shell for each 5000 square yards of area covered : Caliber 75-mm. 105-mm. or 4.7-inch 155-mm. 8-inch 9.2-inch Number of rounds 35 20 10 6 4 II— 24 32 TACTICS AND TECHNIQUE— ARTILLERY (e) Neutralization . — For the continuous neutraliza- tion of an area, the expenditure of shell should be about the following per hour for each 5000 square yards of area covered : Caliber Number of rounds 1st hour Subsequent hours 75-mm. 600 480 105-mm. or 4.7-inch 110 80 155-mm. 60 45 8-inch 35 25 9.2-inch _ 25 20 It is well, when practicable, to precede this fire by a violent bombardment according to the figures given. (f) Harassing. — In harassing fire, it is desirable to use the figures given for neutralization, when the ammuni- tion is available, though any lesser amount will give some harassing effect. (g) Interdiction . — For the interdiction of a given point on a road, the hourly expenditures may be taken as 80 rounds for the 75-mm. gun and 40 rounds for the heavier calibers. The shots should be fired at irregular intervals. A considerable interdicting effect will be obtained with much smaller amounts. Shrapnel may be substituted for shell when conditions are favorable, but the number of rounds fired should not be reduced materially on this account alone. THE LflSARY OF THE tWtZWi n? ouhms To face page 32 PLATE IV CHARACTERISTICS OF FIELD, RAILWAY AND ANTI- AIRCRAFT ARTILLERY Authority : Principally data supplied by the Chief of Coast Artillery and the Chief of Field Artillery CALIBER AND TYPE 1. 75-mm. French gun PROJECTILES RATE OF I^E Time to em- place for firing or change from firing to traveling position g 3 min. Piece Ammunition transport Average rate of march miles per hour 4 Day’s march, miles 25 Kind Shrapnel Shell Shell Weight of Extreme Corresponding Number of Weight bursting range, elevation range lbs. charge, yards degrees zones lbs. a be 16 .185 9700 41 1 11 to 12.65 1.76 8000 34 2 i 12.8 to 14.7 1.35 12000 34 2 i Rounds per piecejpr minute Prolonged d Short Maximum Day of burst possible fire d el f 10 25 300 transport Horse j Kind Caisson Rounds vehicle h 106 k Shrapnel 60 .59 11000 42 1 1 2 7 100 10 min. Tractor, Caisson 1 56 si I t 40 Shell 46 3.24 13000 40 5-ton Truck 49 m Shell 46 4.20 13000 40 1 56 n Shrapnel 95 1.35 11000 40 7 X 2 4 150 15 min. Tractor, Caisson 1 28 3.E t 40 Shell 95 15.2 12600 44 7 or more 6-ton Truck 40 Shell 95 9 12000 41 7 Shell 95 17 17000 40 4 X 2 4 100 6 to 24 hours Tractor, Truck 40 3 i t u 35 ►J hJ Shell 95 16.2 17800 39 2 10-ton L_ £ 5. 8-inch howitzer Shell 200 29 12000 46 4 X 2 3 100 6 to 24 hours Tractor, Truck 20 tu 30 Shell 200 20 12000 45 4 10-ton Q 6. 9.2-inch howitzer, platform Shell 290 34.3 13000 46 6 i X 2 80 8 to 24 hours Tractor, Truck 14 3.5 1 tu 40 w mount 5-ton 7. 240-mm. howitzer, platform Shell 356 45 14000 44 5 i X 2 60 10 to 24 hours Tractor, Truck 10 3.5 tu 40 mount 10-ton 8. 6-inch Trench Mortar Shell 53 11 1800 40 7 4 6 8 150 2 hours to Cars Truck 65 8 60 3 weeks 9. 8-inch gun, all-round fire Shell 200 30 21000 42 X 1 1 80 30 min. Cars Cars 96 20 200 10. 10-inch gun, sliding mount Shell 610 66 28000 45 i i i 50 3 hours Cars Cars 20 200 11. 12-inch gun, sliding mount, Shell 700 90 45000 40 i i . * 40 3 Yl hours Cars Cars 20 200 50-caliber & 12. 12-inch mortar, all-round fire Shell 700 94 16000 45 10 X 1 1 50 30 min. Cars Cars 48 20 200 13.' 14-inch navy gun Shell 1200 154 46000 43 I i 50 31 hours Cars Cars 24 20 200 Shell 1400 88 41000 43 i i i 50 14. 16-inch howitzer Shell 1660 226’ 23000 45 6 hours Cars Cars 20 200 15. 3-inch gun, pedestal mount Shrapnel 15 .17 10000 19 i 5 10 30 Truck Trucks 260 8 60 Shell 15 1.72 10000 • 19 16. 3-inch gun, trailer mount Shrapnel 15 .17 14000 37 i 5 10 30 5 min. Truck Trucks 260 8 60 Shell 15 1.72 14000 > 37 17. 76-mm. gun, truck mount Shrapnel 14.3 .17 8000 25 i 5 10 30 5 min. Truck Trucks 260 8 60 <3 8 Q Manufacture * Weight in Firing Position | Weight Behind Team or Tractor Type of Trail Kind and Amount of Traverse Limits of Elevation Permitted by Carriage Independent or Dependent Line of Sight i r? Type of Recoil Mechanism Length of Recoil | Is Pit Necessary? Is Firing Platform Necessary? I 7^° Variable 75-mm. Gun Model 1920 3700 4600 split PI 30° to 80“ Independent Panoramic hydro- pneumatic 46-18 no no yes 4200 box “S’.. — 7^° 46° ~ "Sstic 42 no no yes 530 “S’- + 45° Dependent Panoramic kL, 28-18 no no no 105-mm. Howitzer Model 1920 3700 4600 sp.it *$r- 7M» 1°.. Panoramic v 3Lc 45-25 no no yes 105-mm. Howitxer Model 1921 3000 4200 axle v 8° ir Panoramic iHatic 42 no no yes 4.7-in. Gun Model 1920 13000 14500 split pintle 60° i Dependent Panoramic 48-21 no no no 155-nun. Howitzer Mode] 1920 13000 14500 split P1 60" n- Panoramic V ^ tic 43-36 no no 155-mm. Gun Model 1920 24000 23000 split P1 60” Dependent Panoramic V H.tio 71-24 no no no 5-in. Howitzer Model 1920 24000 23000 split P1 60° Dependent Panoramic y ... 71-40 no no no PLATE VI PLATE VII AMMUNITION 33 THE NEW AMERICAN SEVENTY-FIVE HI— 1 CHAPTER III Artillery Chemical Shell Paragraphs Introduction 1 Gases Used in American Shells 2 Calibers of Chemical Shell 3 Gas Shell 4 Smoke Shell 5 Fuses for Gas Shell 6 Adjustment of Fire 7 Ammunition Consumption 8 Smoke Screens 9 Conditions Affecting the Use of Chemical Shell 10 Artillery Gas Tactics 11 Gas in the Offensive 12 Gas in the Defensive 13 Smoke Tactics 14 Defense Against Gas 15 Transportation and Storage 16 Markings of Chemical Shell 17 1. Introduction. — (a) All artillery projectiles for land operations, other than shrapnel and high explosive, are grouped under the heading of special shells. The most im- portant of these comprise gas, smoke and incendiary shell, known collectively as chemical shell. Of these, gas stands highest, both in importance and amount used. (b) Artillery is at present the most important instru- ment of chemical offense. At this time it is the sole means of liberating gas accurately at ranges greater than those of gas projectors and Stokes mortars, though airplane bombs for this purpose are future possibilities. Within limits, the use of gas by artillery is independent of meteorological con- ditions and of the positions of friendly troops. The gas car- rying capacity of the projectile is its greatest deficiency. Only 10 to 15% of the shell’s weight can be used for gas as opposed to 50% in the case of the gas projector drum. (c) Gas was first used in shells by the Germans in May, 1915, and its use continued to grow in importance from that time on, so that by the time mustard gas first was used in German shells (July 12, 1917) it had attained the important place it now holds in chemical operations. 34 Ill— 1-3 ARTILLERY CHEMICAL SHELL 35 (d) It has been estimated that during The World War the American artillery put over three or four times as much gas as did all other American gas agencies. It does not necessarily follow, however, that this ratio would have been maintained had the war continued. During the war the approved manufacturing program contemplated that gas shells should comprise 10% of all ammunition, but this was not fully realized. On November 1, 1918, the General Staff, General Headquarters, raised this percentage to 20%, and later the same authority decided that after January 1, 1919, gas shells would form 25% of all shells to be filled. (e) At the date of the Armistice the Germans had 85 different kinds of gas shells. 2. Gases Used in American Shells. — (a) An ex- tensive discussion of the various gases employed by our Chemical Service will form no part of this chapter. A brief description of the principal gases used as artillery shell fillers may, however, aid in considering this special use of gas. (b) As regards their effects on man, gases may be classified as follows : Lethal (deadly). Vesicant (burning the skin). Irritating (affecting the nose, throat and lungs, but not deadly) . Lachrymatory (tear gas). Some gases may combine two or more of these proper- ties. (c) Gases are also classified according to their persis- tency, which is dependent principally upon the rate of evap- oration. The present tendency is to make this division of gases into two classes only — persistent and non-persistent gases. For instruction at these schools it is found more convenient to consider three classes, as follows: Non-persistent. Semi-persistent. Persistent. 3. Calibers of Chemical Shell. — It is intended to supply chemical shell for the following calibers: 75-mm. gun. Pack artillery gun. 36 TACTICS AND TECHNIQUE— ARTILLERY 4.7 inch gun. 155-mm. gun. 155-mm. howitzer. (NOTE. — The question of the use of gas and smoke in larger calibers is still under consideration. During The World War the Germans used chemical shell in all calibers up to 210-mm., and in our own army it was intended to use gas and smoke shell in calibers up to include 240-mm. For the present, the larger calibers will be con- sidered available for instruction purposes at these schools. The present War Department program does not provide for incendiary shell in any caliber, but these are also considered available for in- struction purposes, in the following calibers only, which were those authorized in The World War: 75-mm. gun, 4.7-inch gun, 155-mm. gun and howitzer.) 4. Gas Shell. — Chemical shell in the past have in general been simply the H. E. shell, provided with a special joint between the booster and the shell wall. Ordinarily shell steel is the material out of which all special shells have been made. There are certain variations in weight from standard of all gas shell just as there are for H.E. shell. It is proposed in the future manufacture of gas shells to secure but one weight for each caliber. 5. Smoke Shell. — Smoke shell will be provided in our service for the pack gun, 75-mm. gun, the 4.7-inch gun and the 155-mm. howitzer. (See paragraph 3 above as to larger calibers.) 6. Fuses for Gas Shell. — Instantaneous (super-quick) fuses are necessary in gas shell, as the projectile should, for best effect, burst before any part of it can bury itself in the ground. As all gas fuses are located in the nose of the shell it also follows that a fairly steep angle of fall is re- quired in order that the fuse will certainly operate. Reduced charges when firing gas from the 75-mm. gun are desirable. An angle of fall greater than 10 degrees is re- quired for the 75-mm. gun. On the other hand, if the angle of fall is too steep, partial burial of the shell may result. 7. Adjustment of Fire. — (a) It is necessary to use other than gas shell when firing for adjustment and then to apply the necessary correction for difference in weight when changing to gas shell. (b) Adjustment should be made on some point whose range is approximately that of the target. It should be as close as possible to the actual target without unduly dis- Ill— 7-8 ARTILLERY CHEMICAL SHELL 37 closing the place on which the fire for effect is to be directed. (c) The adjustment for non-persistent gases must be closer than for persistent gases. Consequently, for the former a narrow bracket is sought and then, if there is no wind, the mean elevation of the bracket is used. This eleva- tion is modified if there is wind. (d) With the persistent gases, seek the narrow bracket but disregard wind. In fire for effect, a fire of precision is needed for the non-persistent gases, repeating the fire by range changes of 100 yards if the target is a deep one. 8. Ammunition Consumption. — (a) The amount of gas fired from each caliber to produce certain effects has been calculated for the usual shell fillers and put in the form of tables and charts as described in par. 71, Text-Book on Chemical Service (G. S. S., July , 1921), which reads as follows : “Ammunition Consumption . — Date are given in Appendices VIII and IX for the number of guns and the quantities of am- munition required for various kinds of gas bombardments by 75-mm. and 155-mm. artillery. Appendix VIII gives this data for intensive bombardments where fatalities and casualties are sought. It will be noted that two types of bombardment are in- dicated in Appendix VIII for mustard gas shell; one type for casualties and neutralization, and the other where it is hoped to force evacuation of areas. Appendix IX gives data for harass- ing bombardments, where the only object sought is to force the enemy to mask; casualties are not expected, and such as occur are incidental only.” “Ammunition for other calibers can also be estimated from these tables, in connection with Appendix VII, by considering the relative weights of contents of the various calibers.” Ibid. “As a rule of thumb for phosgene and mustard gas, the nor- mal weight of gas to be delivered at the target for serious casual- ty effect should be 185 pounds per hundred yards square (disper- sion to be allowed in addition).” Ibid. “The dispersion of the shots, which depends of course on the range, causes a decrease in the gas concentration secured, except in the case of neutralizing gas bombardments over large areas. For surprise bombardments this dispersion must in general be allowed for by an increase in the quantity of ammunition dis- charged, as shown in Appendix X, and for neutralizing gases as shown in Appendix XI. The figures given in Appendices VIII and IX are for the net amounts of gas that should be delivered at the target.” Ibid. (b) The most recent experiences in gas firing showed the great economy to be secured by using a powerful tear gas like CA for the purpose of making men wear the mask. It is estimated that for this purpose one pound of that gas equals 500 to 1,000 pounds of phosgene. Ill — 9-10 38 TACTICS AND TECHNIQUE— ARTILLERY 9. Smoke Screens. — (a) The quantities of guns and ammunition required for smoke screens vary with the direc- tion and strength of the wind, and with other weather con- ditions. Weather conditions are never “normal,” hence the difficulty of giving general rules for the rate of fire. The following will probably give sufficient initial density for a wind of about 10 to 14 miles per hour; weather dull, cool, no sun: 75-mm. shell, 2 rounds per 10 yards of front per minute. 4.7-inch shell, 2 rounds per 80 yards of front per minute. 155-mm. shell, 2 round per 30 yards of front per minute. The above is the amount for a wind parallel to the direction of fire, and for establishing the screen, which takes from one to four minutes. Once the screen is formed these amounts can be considerably reduced. In general, one-half the above rate of fire will maintain the screen. The actual quantity of ammunition fired, however, once the screen is formed, is that necessary to maintain an effective screen. This is determined by observation of the smoke cloud. For oblique winds, i the quantities of ammunition stated above will usually be sufficient; for enfilade winds, & the quantities stated. For winds of 20 to 24 miles per hour, double the quantities of smoke ; and for bright, sunny weather, treble the same. The correct amounts are so de- pendent on weather conditions that in general reference to Appendix XIII, Text-Book on Chemical Service, is recom- mended. Smoke screens are placed 100 yards to windward of the target for each 10 feet per second of wind velocity. (b) The above estimates for ammunition consumption are with a view to the production of opaque screens. Less efficient screens can be produced with a smaller expenditure of ammunition. Smaller quantities of ammunition can also be used in very dark or foggy weather, or at early morning or late evening. (c) Good results cannot be expected in winds much over 20 miles per hour. 10. Conditions Affecting the Use of Chemical Shell. — (a) A number of conditions affect the use of chemical shell, especially gas shell, in any particular case. Ill— 10 ARTILLERY CHEMICAL SHELL 39 These are meteorological conditions, character of the ter- rain, and the tactical considerations involved. (b) Meteorologic . — Atmospheric stability is what is desired. Warm, sunny days produce upward air currents and tend to dissipate the gases. The exception is in the case of mustard gas, which is then more readily vaporized and the concentration increased. At night the atmosphere is relatively more stable and conditions are better than by day. For the same reason, foggy days or days of a light drizzly rain are good. A heavy rain tends to wash down the gases. A low barometer tends to the formation of air pockets near the ground. The result is undesirable upward currents of air. Low temperatures hinder the action of the persistent gases. They do not greatly affect the non-per- sistent lethal gases. Wind exercises considerable influence. Non-persistent lethal gases are comparatively ineffective when fired in winds of over 10 miles per hour and persistent or tear gases in winds of over 20 miles per hour. Neverthe- less, when gas is used to aid operations by other troops, tactical requirements must not wait on weather conditions and gas will be used even under the most unfavorable cir- cumstances. (c) Terrain . — Gas is most satisfactorily employed in almost level, undulating districts. The effect of hills and valleys tend to make the gases, which are a little heavier than air, flow down into the lower levels. At the same time this system of hills and valleys may lead to the for- mation of air currents whose direction differs from the gen- eral direction of the wind. The terrain must be considered from this viewpoint, thus making necessary a study of the wind at the enemy's position. Woods have a very great in- fluence on a gas shell bombardment. Often gas can be fired into them when the wind is too strong for good results in the open. High ground or open spaces in general must get a heavier concentration than woods or other inclosed locali- ties. (d) Tactical Considerations . — The location of our own troops with respect to the concentration must be considered. The following table gives the general rules to follow : Ill— 10 40 TACTICS AND TECHNIQUE— ARTILLERY SAFE DISTANCES FOR GAS SHELL OBJECTIVES FROM OUR OWN TROOPS (NOTE: — For safety angles and spread of gas, see paragraphs 48 and 109, Text-Book on Chemical Service.) 1. With Wind Blowing Toward the Enemy - Minimum distances Small shoots Large shoots Non-persistent gases 300 yards | 300 yards Semi-persistent and Per- sistent gases 500 yards 2200 yards 2. With Wind Blowing Toward Our Own Line; or in Calm MUSTARD GAS : Permissible number of rounds of HS per 100 yards front. Amounts may be repeated every six or more hours. For other gases see below. Size of Pounds of Safe distances from own frort line shell Gas per shell No. 500 yds. rounds 1000 yds. No. rounds 2000 yds. No. rounds 3500 yds. and beyond No. rru: ds 7 5 -mm. 1.35 5 12 4*1 90 or more 4.7-inch 4.4 • 2 7 20 15 or more 155-mm. 11.3 1 2 5 18 or more 8-inch 22.5 3 7 or more 9.2-inch 29.45 2 5 or more 240-mm. 37.5 •2 3 or more FOR OTHER GASES: | Multiply above quantities Gas for HS by: Repetitions each CG ' 2| \ hour or more PS. PG. NC. or BA. 2 [ 3 hours or more DA h 4 hours or more CA a ] 4 hours or more The above figures are not to be followed .too rigidly if the tactical situation and the advantages to be derived warrant deviation there- from. When sufficient reason exists, gas bombardments may be placed at closer distances, and our troops warned to take the necessary precautions. Such bombardments may do extensive damage to the enemy, if intelligently employed, while offering only a slight risk or inconvenience, comparatively, to our own troops. (e) In any case it is well to bear in mind the following paragraph of the gas manual (Gas Manual, A. E. F., Part II : Use of Gas by the Artillery) : “The chemical officer must make a careful study of the topo graphical features of the terrain and the meteorological condi- tions applying. After a solution has been arrived at, the chemi- Ill — 10-11 ARTILLERY CHEMICAL SHELL 41 cal officer must be able to advise definitely the chief of staff or artillery commander as to the following: (1) Location of target. (2) Time of shoot. (3) Rate of fire. (4) Kind of gas shell. (5) Number of gas shell required. (6) Object to be accomplished.” 11. Artillery Gas Tactics. — (a) All artillery gas firing is of two kinds ; casualty producing, or intensive, and neutralizing. There may be various combinations of these two which go under different names, such as counter bat- tery, harassing, interdiction and the like, but these are the two basic divisions. (b) Casualty producing or intensive fire is intended to produce casualties. Lethal gases are employed and, as they are of low persistency, the concentration must be built up quickly. This is secured, for any given number of rounds, by using as many guns as possible firing simultaneously with a high rate of fire. The usual length of time is about two minutes, although under very favorable conditions, such as dead calm in thick woods, or at night, fire may last for five minutes as a maximum. (c) Neutralizing fire is intended to paralyze or greatly reduce human activity by wearing down morale and caus- ing the mask to be worn for long periods of time. For this purpose recourse is generally had to persistent gases, pre- ferably to mustard. This concentration does not have to be quickly built up. Fewer guns and longer time to fire are permissible. (d) For counter battery work a burst of lethal gas is often employed, followed by a slow neutralizing fire with persistent gas. (e) Harassing fire is usually effected with tear gas, which makes long continued wearing of the mask obligatory to escape its annoying effects. There are also many strategems that can be practiced. Amongst them may be mentioned mixing lethal gas with a blinding smoke cloud; mixing gas with high explosive; firing a nauseating or coughing gas causing the removal of the mask and following it with a burst of lethal gas; firing gas at night where men may be resting with masks off and Ill— 11-13 42 TACTICS AND TECHNIQUE— ARTILLERY possibly not readily at hand ; mixing a small amount of gas in our own rolling barrage, not enough to do real harm but enough to induce the enemy to mask. About one gun per battery (25%) can be so used. With a four-mile-per-hour wind, our troops can follow this barrage in one-half minute without their masks. However, to sacrifice 25% of the guns in barrage for this artifice is open to debate. This by no means exhausts the list of devices whereby gas may be fired with increased damage to the enemy. 12. Gas in the Offensive. — Gas may be used in pre- paration for the attack, during the attack, during lulls in the action and while consolidating a captured position. As previously stated, the offensive usually demands the use of non-persistent gases in areas over which our troops can be expected to advance within a short time. It is necessary in an offensive to calculate a safe interval as to time before the attacking troops arrive at successive stages of their ad- vance when using CG and DA gas.* This calculation must be made both for the preliminary bombardment and for any gas fired during the course of the attack. For lulls in the action, and for support during consolidation, semi-persis- tent or persistent gases may also be used, depending upon the probable time elapsing before another advance. If no further advance will be made for a number of days, use persistent gas, especially if dangerous counter attacks must be warded off. 13. Gas in the Defensive. — In defense or in retreat the use of persistent gases is the rule, mustard preferred. The area vacated must be made as untenable as possible for the enemy, and for the maximum length of time. Mus- tard surpasses all other gases for this purpose. This does not mean that gas shell is necessarily the best type of pro- jectile to use in all cases. The effects of mustard are not im- mediately apparent, and the hostile advance may be so ra- pid that casualties must be inflicted in the shortest space of time and in the greatest numbers. In such instances, re- course is had to shrapnel and high explosive shell or to quicker acting gases. In any stabilized condition, such as *CG, Phosgene; DA, Diphenylchlorarsine. Ill— 13-16 ARTILLERY CHEMICAL SHELL 43 obtained during the first three years of The World War, persistent gas can be freely used. 14. Smoke Tactics; — Smoke shell is used by artillery for four purposes; 1st, to screen our own troops; 2d, to blot out enemy observation by a concentration of smoke around his observation stations ; 3d, to signal to the infantry during the barrage and 4th, as a feint. 15. Defense Against Gas. — (a) This subject is con- sidered only in so far as concerns certain precautions that are taken by batteries against gas shell. (b) Gas defense measures in general form no part of this discussion. The special phase of gas defense to be dis- cussed is that of gas positions for batteries of our own troops. Arrangements for such positions usually are made when a stabilized condition arises ; but they should be given some consideration even during conditions of movement. These positions are alternative positions located within 300 to 500 yards of the regular battery positions. Firing data are prepared for them and all other necessary arrangements made so that, in case the battery receives a shelling of per- sistent gas which makes its regular position no longer ten- able, the guns can be moved into the gas position (by hand) if necessary. The material taken to the new position all should be cleansed thoroughly of gas, usually by wiping off with a strong solution of chloride of lime. (c) Gas positions are sufficiently remote from the po- sitions of neighboring batteries so that they neither draw fire upon those batteries, nor receive fire intended for them. In the event of large artillery concentrations in restricted areas — as in preparation for a great offensive — a strict ad- herence to this principle is not always possible. This does not alter the principle, however, that alternative positions are provided, when practicable, as insurance against neu- tralization or destruction. 16. Transportation and Storage. — In general, gas projectiles are safe to handle, but personnel doing so should carry masks. The mask is worn if working amidst leaky projectiles, and, in the case of mustard gas, special clothing and gloves are worn. Leaky gas projectiles are disposed of at once, either by firing, burying or exploding them in Ill— 16-17 44 TACTICS AND TECHNIQUE— ARTILLERY piles. Leaky mustard gas shells, however, should not be fired. Gas shell should be stored in a cool place. The gas ammunition at battery positions should be placed in small piles, apart from other ammunition, and on what is gener- ally the leeward side of a battery, to minimize the danger in case of being struck during bombardment of the position. Each pile should not exceed, 100 rounds for 75-mm. 50 rounds for 4.7-inch. 25 rounds for 155-mm. 17. Markings of Chemical Shell.— (a) These shell are all painted and marked so as to be readily recognized. The body is painted gray and, stenciled lengthwise of the shell in black letters, are the words “Special — Gas, Smoke or Incendiary,” as the case may be. Around the body of the shell are painted stripes of varying numbers and col- ors. White stripes are used for non-persistent gases, usually lethal. Red stripes are used for persistent gases. Yellow stripes are used for smoke. (b) The number of stripes is greater for the degree of indicated quality. For example: phosgene (CG), non- persistent, has two white stripes; chlorpicrin (PS), semi- persistent gas, has a red and white stripe : chlorpicrin and stannic chloride (NC) has three stripes, red, white and yel- low because it is a semi-persistent gas that gives off smoke on burst; mustard gas (HS), persistent, has three red stripes. (c) There is painted on the shell also a series of crosses for 75-mm. ammunition, and a series of squares for larger calibers, to indicate departures of weight from the standard projectile. The greater the number of crosses or squares the greater the variation from standard. Below are the weight markings for 75-mm. ammunition. The weights of the shell are the same as for HE shell and are marked as follows : Ill— 17 ARTILLERY CHEMICAL SHELL 45 From lbs. oz. To lbs. oz. Weight mark just above driving band 10 11 11 0 L 11 0 11 5 + 11 5 11 11 + + 11 11 12 0 + + + 12 0 12 5 + + + + IV— 1-2 CHAPTER IV Artillery Ammunition Supply Paragraphs General 1 Agencies of Ammunition Supply 2 Use of Ammunition Supply Agencies 3 Normal Loads Held in Reserve 4 Accumulations of Ammunition 5 Kinds and Amounts of Ammunition Carried 6 Replenishment of Ammunition 7 Ammunition for Corps Artillery Attached to a Division 8 The Artillery Brigade Munitions Officer 9 Munitions Reports 10 Small Arms Ammunition 11 System Shown by Graphics 12 1. General. — Ammunition is a Class IV supply. Re- quisitions therefor by an army (the army being considered herein as a tactical unit) must be approved by the comman- der in chief of the field forces. This approval comes through G4, general headquarters, who notifies the army of the amounts of ammunition allotted to it and from what depots of the communications zone the ammunition will be supplied. The depots are notified as to the amount of ammunition to be furnished the army. In allotting ammunition for an army, general headquarters is guided by the plan of future operations. 2. Agencies of Ammunition Supply. — In consider- ing the supply of ammunition to front line organizations, it is well, in order to gain a clear idea, to take up the ammu- nition in the rearmost depots of the communications zone and follow it forward. In doing so the following agencies are found, from rear to front. (a) Branch ammunition depots in the communications zone (in the base, intermediate, and advance sections if the communication zone be subdivided). These depots are on standard gauge railroads, and for reasons of safety are located away from cities and towns. Ammunition goes for- ward from these depots, in train load lots, to the army am- munition depots. 46 ARTILLERY AMMUNITION SUPPLY 47 (b) Army ammunition depots, also on standard gauge railroads, which contain the army reserve ammunition of all kinds. As seen in (a), they are supplied by train load lots from the branch ammunition depots of the communi- cations zone. (c) Advance army depots; these are advanced off- shoots of the army depots and are supplied therefrom. They contain few types of ammunition ; often a single type only. They are on standard gauge railroads whenever practicable and should always be on a railroad of some character, over which they are supplied. In special cases, they may be sup- plied by truck train, either wholly or in conjunction with railways. No rule as to the distance of army advance de- pots from front lines can be given as it varies widely with the mission of the army. In stabilized situations, or when the army is on the defensive, they are generally from twelve to twenty miles from the front lines, while, just prior to a big offensive, they may be advanced to within three miles. (d) Refilling points which are points at which the divi- sion trains are refilled. A refilling point may be: (1) An army ammunition depot. (2) An advance army ammunition depot. (3) A corps ammunition park (which is the dumped ammu- nition from the corps quartermaster train). (4) A point at which ammunition is transferred from the transportation of higher units to division transportation. The use of (3) or (4) as refilling points is exceptional. (e) Division ammunition dumps, which contain all types of artillery ammunition used in the division. If prac- ticable they are located on railways and in any case must be on roads suitable for trucks. They are supplied from ad- vance army depots by division transportation (ammunition train, field artillery brigade) which, in special cases, may be assisted by corps or army transportation. (f) Ammunition distributing points, which are points at which regimental transportation (combat trains) receives ammunition from ammunition trains. (g) Regiment and battalion ammunition dumps which contain ammunition for a particular regiment or battalion. They should be located on good roads with suitable circula- tion facilities. They are supplied by any one of the follow- ing methods: 48 TACTICS AND TECHNIQUE— ARTILLERY (1) By the ammunition train, artillery brigade, direct from refilling point; (2) By truck section and wagon section of the ammunition train working in relays, the truck section working from refilling point to a transfer point and the wagon section from this transfer point to ammunition dumps; (3) By truck section, wagon section, and combat trains working in relays, the truck section from refilling point to trans- fer point, the wagon section from transfer point to distributing point, and the combat trains from distributing point to ammuni- ion dumps; (4) By ammunition train (either truck or wagon section) to distributing point and by combat trains from there to ammuni- tion dumps; (5) In especially favorable cases the brigade ammunition train can deliver ammunition direct to the battery positions. 3. Use of Ammunition Supply Agencies. — From the foregoing it is seen that the artillery ammunition for the division generally is drawn from advance army depots by the ammunition train, field artillery brigade. In more or less stabilized situations, if the advance depot be well up and good roads exist, the ammunition train can deliver the ammunition directly to battery positions. Often it is ad- visable to relay the ammunition, the motor section of the ammunition train accomplishing the rear part of the haul, and the horse section working between the motor section and the distributing point, from which point the battalion combat trains carry the ammunition forward to the gun po- sitions. 4. Normal Loads Held in Reserve. — The caissons of the battalion combat trains maintain, in close vicinity of their bivouacs, their normal loads of ammunition, which they may readily pick up as occasion demands. This am- munition is a reserve to be drawn on only in emergency. Every effort is made to keep up supply from rear to front without using it. Similarly, it is normal for the ammuni- tion train, artillery brigade, to dump its normal load at its bivouac, and to endeavor by every means to maintain the supply without drawing on the normal load. 5. Accumulations of Ammunition. — In stabilized situations, particularly just prior to an offensive, it may be desirable to accumulate considerable ammunition at distri- buting points and battalion dumps. In open warfare, how- ever, or when on the defensive, it is unwise to accumulate great stocks of ammunition in forward areas, hence, except IV— 5-7 ARTILLERY AMMUNITION SUPPLY 49 for the dumped loads of the ammunition train, artillery bri- gade, and the battalion combat trains, it is better to supply directly from advance army depots. 6. Kinds and Amounts of Ammunition Carried. — The kinds of ammunition to be carried in the division de- pend upon the orders issued for the contemplated operations — generally the proportions are: shell 50% to 75%. shrapnel 40% to 15%. smoke 10%. Gas may be carried if conditions warrant, but is not carried habitually ; hence there is normally no gas available in the division unless special provision has been made there- for. The amounts of ammunition carried within a division are as follows (75-mm. guns) : Within the regiment (firing battery 177, battalion combat train 159) 336 rounds per gun. In the ammunition train of the artillery brigade 155 rounds per gun. Total 491 rounds per gun. 7. Replenishment of Ammunition. — (a) When the division is part of a corps, there is carried in the corps train (Quartermaster Corps) 150 rounds per gun for the divi- sion 75-mm. guns, which amount is in addition to that car- ried in the division. This corps train ammunition is a roll- ing reserve and is not to be drawn upon except in grave emergencies. Hence it may be said that the division artil- lery has within the division 491 rounds per gun and that ammunition beyond that amount must, except in great emergency, be brought from army ammunition depots. (b) It is not difficult to visualize a situation in which, in one day of hard fighting, the division artillery would use this amount of ammunition. It is well, therefore, to con- sider how this ammunition is to be replenished and a sup- ply maintained at the guns. (c) The agency through which this is accomplished is the ammunition train of the artillery brigade which carries, when all trucks and wagons are in commission, approxi- mately one-half a day of fire. IV— 7-8 50 TACTICS AND TECHNIQUE— ARTILLERY (d) To supply daily one day of fire, therefore, involves two round trips of this train, plying between the ammuni- tion depot and the distributing point (where the battalion combat trains draw for the batteries). (e) Roughly one-third of the ammunition in the am- munition train, artillery brigade, is hauled in the wagon sec- tion. If the army depots are well to the rear, the wagon section cannot make two round trips per day. In this case an additional burden is imposed on the truck section, and cases may arise wherein the truck section alone will have to do all the carrying between army depots and distributing points. (f) The truck section alone carries approximately one- third day of fire for the division artillery, therefore, if it is the only agency carrying ammunition forward from army depots to distributing points, it will have to make three round trips daily. Whether or not this is practicable in any situation depends upon the condition of the roads, the amount of traffic passing over them, and the distance to the army depot. (g) However, as the average day in and day out ex- penditure of ammunition in the division artillery is esti- mated as one-third of a day of fire, the truck section of the ammunition train, artillery brigade, was organized to carry that amount. Whenever a greater consumption can be fore- seen, it must be arranged for in advance whenever possible, by bringing up stocks of ammunition and locating them so that they are readily available to combat trains. This us- ually is accomplished by establishing advanced army am- munition depots in forward areas. 8. Ammunition for Corps Artillery Attached to a Division. — (a) When a regiment of 155-mm. howitzers is attached to a division it brings with it, within the regiment, 162 rounds per gun (firing battery 42, battalion combat train 120) . The regiment is as a rule accompanied by a por- tion of the ammunition train, corps artillery brigade, which carries an additional 60 rounds per gun; hence there is generally available 222 rounds per gun. (b) While the howitzer regiment remains attached to the division, the transport company is handled as a part IV — 8-11 ARTILLERY AMMUNITION SUPPLY 51 of the division artillery brigade and assigned for operations to the ammunition train, carrying ammunition between army depots and battery positions. The battalion combat trains of the 155-mm. regiment are motorized, and nor- mally accompany the ammunition train, artillery brigade, to army depots. It thus follows that 155-mm. ammunition in a division is usually brought directly from army depots to battery positions. 9. The Artillery Brigade Munitions Officer. — It is a duty of the artillery brigade commander, under general staff coordination, to insure the proper supply of ammuni- tion for the division artillery. This duty he executes through one of his staff officers, the artillery brigade munitions offi- cer. Generally this officer is charged with all details relating to the procurement and distribution of artillery ammunition within the division, including staff direction of the operation of the ammunition train, artillery brigade, whenever it is released to the artillery brigade commander. He is charged with all records and reports relating to ammunition. He re- commends to G4 sites for ammunition establishments and is responsible for camouflage, safety precautions and proper care of ammunition from the time it is received by the artil- lery brigade until turned over to the regiments. This offi- cer is also the supply officer of the headquarters battery of the field artillery brigade. He has one sergeant as ammu- nition clerk and one corporal as supply clerk. 10. Munition Reports. — Artillery ammunition resup- ply in the combat zone of a theater of operations is based on reports of expenditures. Briefly, it may be said that they are made daily as of a prescribed hour and may be by phone or in writing, usually both. Batteries report to their regimental munitions officer by phone. Regimental muni- tions officers report to artillery brigade munitions officer by phone and by written copy. The division artillery brigade munitions officer reports to corps munitions officer (the lat- ter a staff officer of the corps artillery headquarters) send- ing a copy to G4 of the division. 11. Small Arms Ammunition. — No mention has been made herein of small arms ammunition for artillery units. The expenditure of this type of ammunition is usually so IV — 11-12 52 TACTICS AND TECHNIQUE— ARTILLERY small as to be insignificant. When additional ammunition of this type is needed it is obtained by call on the division ordnance officer. 12. System Shown by Graphics. — The system of am- munition supply and of ammunition reports are set forth graphically in Plates VIII and IX. ARTILLERY AMMUNITION REPORTS ( From On/ Logistics) PLATE YUL ARTILL ERY AMMUNITION SUPPLY FA Regis ( From D/v Logistics) PLATE IX V— 1-3 CHAPTER V Artillery Firing Paragraphs Section I. — General 1-3 Section II. — Preparation of Fire 4-21 Section III. — Firing Over Obstacles 22-23 Section IV. — Ballistics 24-31 Section V. — Dispersion. Probability 32-39 Section VI. — Firing 40-49 Section VII. — Aerial Observation 50-52 Section I General Recent Developments 1 Old Methods Essential 2 Duty of Artillery 3 1. Recent Developments. — Artillery firing changed as a result of the war. But the changes were not, as is fre- quently believed, in the nature of discarding the old, but rather in adding to it, developing and refining it, when time and situation permit. The accomplished artilleryman of today must have a larger technical knowledge than formerly. For example, corrections for atmospheric conditions have developed greatly, although applicable only under certain conditions. 2. Old Methods Essential.— On the other hand, the older, cruder methods in use before the war are still sound, still necessary, and cannot be neglected without seriously impairing fighting efficiency. 3. Duty of Artillery.— It is the aim and duty of the artillery to deliver effective fire when and where needed. The problem of delivering effective fire on a given point at a given time is largely one of technique. To insure that the given point and time meet the needs of the infantry and the situation in general is a tactical problem; in fact, it is the essence of the tactical handling of artillery. The discus- sion in this chapter is confined to technique. 55 V— 4-6 56 TACTICS AND TECHNIQUE— ARTILLERY Section II Preparation of Fire Paragraphs Definition 4 Mechanism of Laying 5 Kinds of Laying 6 Laying for Direction 7 Finding the Deflection 8 Angular Measurements 9 Systems of Deflection Graduation 10 Map and Compass Laying 11 Deflection Difference 12 ’Laying for Elevation 13 Finding the Site 14 Finding the Range 15 Finding the Elevation 16 Time Fire 17 Summary of Firing Data 18 Refinements of the Preparation of Fire 19 Ballistic Corrections 20 Conclusions as to Preparation of Fire 21 4. Definition. — Since the preparation of fire is an indispensable preliminary to all artillery firing, it is con- sidered first. The preparation of fire is finding the firing data, which are defined to be “the information and com- mands necessary to enable the gun squads to accomplish the orderly, rapid and accurate service of the pieces.” 5. Mechanism of Laying. — (a) The object of laying is to give the piece such direction, and such an elevation (or depression) in a vertical plane, that the projectile will reach the target. (b) The cannoneer executes commands mechanically by means of laying instruments; and while he must have a certain amount of skill and dexterity, the responsibility for successful results rests mainly with those determining the announced data. 6. Kinds of Laying. — L aying may be direct or indirect. (a) For direct laying, the piece is sighted for direction and elevation on the target itself which must be visible to the gunner. (b) For indirect laying, the piece is given direction by sighting on any convenient designated point (aiming point), and elevation by a quadrant or level. The cannoneers do not, of necessity, see or know the target. V— 6-7 PREPARATION OF FIRE 57 (c) Indirect laying is easily the predominating method. It has a number of advantages. The pieces can fire effec- tively from concealed and protected positions. An aiming point is distinct and definite ; the target, even when visible, is generally vague and indefinite. Indirect laying thus is possible when direct laying would be either impossible or very difficult. Indirect laying affords decided advantages of collective control and eliminates difficulties of target desig- nation. It operates to place the brain work of firing on the officer, and makes the soldier’s work more purely mechanical. (d) Direct laying however is decidedly superior for moving targets. 7. Laying for Direction. — (a) This operation is ac- complished by means of the sight, a typical example of which is the panoramic sight. It is telescopic and is mounted on the left side of the carriage. The eye piece is stationary, while the objective lens is carried in a head which rotates about a vertical axis. Vision through the sight is the same as for an ordinary telescope, regardless of the position of the rotating head. The construction is periscopic to the ex- tent of about six inches. (b) The rotation of the head is measured by a scale graduated in effect clockwise from 0 to 6400 mils.* The sight mounting is, such that when the setting is 0 (or 6400) , the line of sight is parallel to the axis of the bore of the piece; when the setting is 1600, the line of sight is to the right and perpendicular to the bore ; and when 3200, to the rear. A setting of 1000 is indicated in Figure 1. *It is assumed that the student is familiar with the mil and its properties. 1 mil = 3% minutes; 18 mils (more exactly, 17.778) =1°. There are 6400 mils in a circle. 1 mil subtends a portion of the cir- cumference equal to Viooo of the radius, very closely; in other words, a mil, for approximate calculations, may be taken as the angle whose sine or tangent is Mooo- Minutes x3 = mils (very closely). One mil subtends one yard at 1000 yards’ range, 5 yards at 5000 yards’ range, etc. V— 7 58 TACTICS AND TECHNIQUE— ARTILLERY yVuzz le Figure 1. — Deflection graduation of sight. (c) Thus it can be seen that if the sight be set at 0, and the piece with the sight traversed (moved in direction) until the line of sight is directed on the aiming point, the bore also will be directed on the aiming point. Similarly, a sight setting of 1600 will cause the bore to be directed 1600 mils to the left of the aiming point, and so on. In other words, the piece can be pointed in any direction by varying the setting of the sight, but using the same aiming point. (d) If then we measure the angle clockwise from the target to the aiming point, set the panoramic sight at this angle, and direct the line of sight on the aiming point by traversing the piece, — the bore will be directed on the tar- get. The angle set on the sight is called the deflection . (e) Even though the deflection be measured accur- ately, the projectile in general will not fly in exactly the V— 7-8 PREPARATION OF FIRE 59 correct direction, due to various causes, such as wind, drift, movement of the target, etc. The deflection must be cor- rected as far as practicable to offset these influences. For direct laying, since the aiming point is the target itself the deflection would be 0 but for these influences; therefore the actual deflection consists solely of the correction for them. 8. Finding the Deflection. — (a) For direct laying, the deflection determination consists simply of calculating or estimating the correction for the influences, mentioned in the preceding paragraph, which cause the projectile in flight to move from the plane of fire. Direct laying is generally hurriedly prepared, however, and refinements are often impracticable; so that frequently the deflection is announced as 0, the necessary correction being made as a result of the observation of the first shots. (b) For indirect laying, the deflection determination is more difficult. The simplest method is to place an in- strument at the gun position and measure the angle from the target clockwise to the aiming point, which gives the deflection directly. This method is applicable when a satis- factory map or equivalent graph is available, with the tar- get, aiming point, and gun position located on it; or on the ground, in the exceptional case when the target is visible from the gun position. This direction and origin of meas- urement are important, and must become a fixed habit; otherwise errors and confusion will result. (c) The problem generally is more complicated, since ordinarily the target cannot be seen from the position of the piece, or other conditions may exist which prevent the use of the foregoing method. When working on the ground, two cases arise, (a) a distant point (Figure 2) is used as an aiming point, and (b) the battery commander’s instrument at B (Figure 3) is used as an aiming point. (d) For (a), the angle TGP, Figure 2, is the deflection sought, T being the target and G the piece. This angle can- not be measured directly. The battery commander’s post, B, is probably the nearest point from which the target, piece, and aiming point can be seen. But if the deflection V— 8 60 TACTICS AND TECHNIQUE— ARTILLERY P Figure 2. — Deflection determination, using an aiming point. be measured at B as the angle TBP, it will be incorrect due to the displacement of B from G. Draw BT' parallel to GT, and BP' parallel to GP. Then the angle T' BP' is exactly the deflection sought, since its sides are parallel to those of the angle TGP. This is called the parallel method of finding the deflection. Although simple in principle, the parallel method pre- sents some difficulty practically, because there is nothing on the ground to establish the parallels T'B and BP'. If time is important they must be estimated by eye, which can be done with surprising accuracy after a little practice. If more time is available, the angle TBP can be measured ac- curately and corrected by the angular offsets TBT' and PBP'. The offsets can be calculated more or less accur- ately depending on the time available. For example the angle TBT' in mils is roughly BG in yards divided by BT in thousands of yards. The angle PBP' can be obtained in a similar manner. V— 8 PREPARATION OF FIRE 61 To summarize case (a) : An instrument (graduated clockwise) is set up at B and oriented, not on T, but on T', so that BT' is parallel to GT. Without disturbing the ori- entation, it is pointed, not on P, but on P', so that BP' is parallel to GP. The instrument reading is then the deflec- tion sought. (e) Reciprocal Laying . — For case (b) (par. 8c), the method is similar. The instrument, oriented on T' (Fig- ure 3), is pointed on G. r Figure 3. — Deflection determination, using reciprocal laying. The angle T'BG thus obtained is not the deflection sought, but differs from it by exactly 3200 mils. If T'BG is less than 3200, as in the figure, 3200 is aded to it; if T' BG is greater than 3200, 3200 is subtracted from it. The result is the deflection sought. The correctness of this rule can be verified by inspection of Figure 3 and similar diagrams. This method, where the battery commander “lays” on the piece as an aiming point and the piece on the battery commander’s instrument, is called reciprocal laying. The term perhaps is applied more correctly to two pieces, one of which is laid in the desired direction and is used by V— 8-12 62 TACTICS AND TECHNIQUE— ARTILLERY the above method to assist in laying the other piece parallel to itself. 9. Angular Measurements. — The angular measure- ments involved in finding the deflection preferably are made by instruments such as the aiming circle, scissors tele- scope, and the like. When instruments are not available, the determination still is possible, but naturally with less accuracy. The means employed would be handbreadths, the battery commander’s ruler, the field glass, or similar improvised devices. 10. Systems of Deflection Graduation. — The con- tinuous deflection graduation from 0 to 6400 is not used on all service materiel. Some sights and instruments are grad- uated from 0 to 3200 twice. The advantage of this gradu- ation is that it eliminates the arithmetical calculation in reciprocal laying (par. 8e). The sight of the French 75- mm. guns has four quadrants each graduated from 0 to 1600 mils. These and other features cause the deflection deter- mination to differ in details for each type of materiel; the essential principles however are the same for all. 11. Map and Compass Laying. — The methods of de- flection determination described in the foregoing para- graphs are by no means the only ones in current use ; there are many variations and refinements of these methods which are beyond the scope of this discussion. Frequently it is necessary to transmit the direction of the target to an instrument near the battery by means of an azimuth, true, magnetic, or referred to the map grid. With these data, the instrument is oriented in the direction of the tar- get, and the pieces are directed by reciprocal laying. The methods are so complete that in general a piece can be directed on a known target regardless of conditions, such as, darkness, fog, dense woods, or even when the piece is in a closed casemate involving the use of mirror laying. 12. Deflection Difference. — (a) Thus far only a single piece has been considered, while the battery comman- der has ordinarily to find the deflection for the four pieces of his battery. (b) In Figure 4 the pieces G„ G 2 , G 3 , and G 4 are laid with parallel lines of fire (parallel fire), by means of a PREPARATION OF FIRE 63 Lines of fire Figure 4. — Deflection difference. common aiming point P. The deflections are d lf d 2 , etc., as indicated. G 2 P x , G 3 P 4 , and G 4 P 4 are all parallel to G 4 P. Similarly G 3 P 2 and G 4 P 2 are parallel to G 2 P, and G 4 P 3 is par- allel to G 3 P. Thus it will be seen that the deflections de- crease successively from the right (1st piece) to the left (4th piece) . d 2 is less than d 4 by the angle P 4 G 2 P, or G 2 - PGj ; or roughly one platoon front, G 2 G 4 , divided by the dis- tance to the aiming point, or 20 (usual distance between guns) G X P (in thousands) Also d 3 is less than d 2 , and d 4 than d 3 , by the same amount. (c) Thus, if the pieces are equally spaced, the deflection of adjacent pieces for parallel fire differs by a constant V— 12-13 64 TACTICS AND TECHNIQUE— ARTILLERY amount called the deflection difference. The deflection dif- ference is announced with respect to a certain piece, usually the right, for which the deflection was determined. A com- mand might be, for example, “Deflection 2235; on No. 1, close 5.” All pieces set at 2235. “Close 5” is the deflec- tion difference. Close means to decrease the deflection, all pieces except No. 1 responding to the command. No. 2 de- creases its deflection by 5, No. 3 by twice 5 or 10, and No. 4 by three times 5 or 15, the result being to bring the lines of fire closer together. (d) For nearby aiming points, the deflection difference is so large that it would introduce serious errors to assume it constant for all pieces. For this reason, nearby aiming points (nearer than 1000 yards) are avoided. In case a distant aiming point is not available, reciprocal laying must be used. In this case a deflection is announced for each piece, or it may be announced for one piece and the other pieces laid parallel as already described. 13. Laying for Elevation. — (a) This operation dif- fers for the two methods of direct and indirect laying. But in both cases a range setting or elevation in angular units is announced to give the bore an elevation correspond- ing to the range of the target. 7 " // Figure 5. — Influence of site with indirect laying. y— 13 PREPARATION OF FIRE 65 (b) The problem of laying for elevation is illustrated by Figure 5. G is the piece, T the target, and GH a hori- zontal through the piece equal in length to the range of the target. E is the elevation which must be given the piece to reach as far as the target on horizontal ground. But if the piece were fired at this elevation at the target shown, the projectile would fall short by PT, due to the target being more elevated than the piece. This elevation of the target in angular units is called the site, or angle of site , s. It is seen that if the piece be given an elevation of E and S* the projectile will reach the target. (c) For direct laying, the range of the target is set on the range scale of the sight mounting, in much the same manner as for an infantry rifle. The piece with the sight then is elevated till the line of sight passes through the target. The sight mounting is constructed so that the set- ting of the range places the bore above the line of sight by an amount appropriate for the range, and the operation of bringing the line of sight on the target corrects for the site of the target, accomplishing the correct laying of the piece for elevation. (d) For indirect laying, two methods are used: (1) The site is set on a separate scale provided; and the range is set on another scale, in some cases the same as used for direct laying. The mechanism is constructed so that, these settings having been made, the proper eleva- tion is given by elevating the piece by means of a hand- wheel until a bubble is centered. (2) The piece is laid by a quadrant placed on the piece itself. The elevation set on the quadrant is obtained by the expression, Eq=Er plus s where Er is the elevation corresponding to the range of the target, and is taken from the range tables ; and s is the site, plus if the target is higher than the piece, and minus if the target is lower than the piece. This is called quad- rant laying , and is used for very accurate work, when speed is not important, as in rolling barrages or the destruction of material objectives. V — 14-15 66 TACTICS AND TECHNIQUE— ARTILLERY 14. Finding the Site. — (a) The site is necessary only for indirect laying. It may be determined by direct meas- urement on the ground, or from a contoured map. An esti- mation of site, unless comparative, generally is worthless. It is better to use zero than estimation, unless the site is so considerable that its sign at least is reasonably certain. (b) The site is measured directly on the ground by means of the aiming circle, clinometer, or similar instru- ment, equipped to measure vertical angles from the hori- zontal. The measurement is taken from the positior of the piece. If the target cannot be seen from this position, a position must be selected from which the target can be seen and the measured angle modified appropriately. The methods of doing this need not be considered here. (c) The determination of the site from a map is shown by the following example : The piece is on contour 520; the target elevation is 610 feet. Map range, 3700 yards. What is the site of the target? Solution : The target is 610-520=90 feet=30 yards above the piece. The site is plus and equal to ** 0 / 3*7 mils, or 8 mils, or 27'. (d) Care must be taken to give the site its proper sign. 15. Finding the Range. — (a) Three methods are used: (1) The map, (2) Range finder, (3) Estimation, in the order of general accuracy. (b) The map ordinarily is more accurate than the range finder ; but if the map is poor and the range finder is reasonably well handled, the latter may be more accurate. The accuracy of a map range frequently can be increased by topographical operations to locate the target and piece accurately: time is an important factor in such work. (c) The service range finder in the hands of a reas- onably well trained officer or soldier is some four times more accurate than estimation. Its probable error for artillery ranges up to 5000 yards is about 100 yards. The range finder is in most cases more rapid than the map. It is the only reliable means of determining the range to a y — 15-16 PREPARATION OF FIRE 67 rapidly moving target which is visible only a short time, unless it is possible to use previously prepared data. 16. Finding the Elevation. — (a) As shown in a pre- ceding paragraph, some types of materiel have scales grad- uated in range, in which case the elevation need not be de- termined. Such graduations however are correct only for one kind of ammunition. During the war, there were as many as 20 kinds of ammunition issued for the 75-mm. gun at one time, so that, even though there be scales graduated in range, a fictitious range setting must be used when firing other ammunition than that for which the scale is graduated. (b) When the scales are not graduated in range, or when quadrant laying (par. 13) is used, it is necessary to know the elevation corresponding to a given range. For each type of artillery, there are issued range tables, giving, for each range and kind of ammunition, the range setting, elevation, and other useful data. Such tables are given in abbreviated form for the 75-mm. gun and for the 155-mm. howitzer in the appendices. Ranges are given in meters since range scales are graduated in this unit.* When the range has been found, the use of the range tables to find the range setting or elevation is best ex- plained by the following examples : (1) The range has been determined as 1500 meters. What range should be announced for the 75-mm. gun, using shell with direct laying? Solution : In the range tables, opposite the range 1500, is found the required value, 1550. The range scale was graduated for French shrapnel; the shell is a lighter projectile, has a diff- erent muzzle velocity, and the range scale graduations are not directly applicable. (2) The range has been determined as 7000 meters, and the site as plus 24 mils. What data should be announced in order to lay the 155-mm. howitzer for elevation by means of the sight mountings? Solution : Since there is no stated condition to make this inadvisable, the smallest practicable charge will be used. Charge 5 theoretically will reach this range, but conditions might well give a short with the maximum range; therefore Charge 6 is *The metric system was adopted for use in France. For future manufacture, range scales will be graduated in yards when linear units are used. Meters can be converted to yards by adding ^o; thus 7500 meters =8250 yards (8200 more accurately). Yards can be converted to meters by dividing by 11 and multiplying by 10; thus 8200 yards = 7455 meters (7500 more accurately). y — 16-19 68 TACTICS AND TECHNIQUE— ARTILLERY chosen. The required data are then: Site, plus 24; charge 6; elevation 396. (3) The range has been determined as 4500 meters, and the site as plus 14 mils. What data should be announced in order to lay the 75-mm. gun for elevation by means of the gunner’s quad- rant, using shell? Solution: The elevation for 4500 meters is 180 mils; the quadrant elevation is then 180 plus 14, or 194 mils. The data required are then; Shell; quadrant, 194. 17. Time Fire. — Time fire is fire with projectiles, either shell or shrapnel, equipped with time fuses set to give bursts in air before the projectile strikes. In this case, an additional element of the firing data is necessary, the fuse setting. This may be the tabular time of flight given in the range tables, or a special column of fuse settings may be included in the tables. The fuse setter for the 75-mm. gun is graduated in range to avoid reference to the range tables. There is also an auxiliary scale, called the corrector or corrector scale , to facilitate adapting the range scale to the special condi- tions existing at the moment of firing. 18. Summary of Firing Data. — F rom the foregoing discussion, the firing data and the methods of obtaining them may be summarized as follows, in the order in which they usually are announced: Aiming point or target. — Former for indirect laying; latter for direct laying. Aiming point may be a distinct and distant natural object, or an instrument near the pieces. Deflection. — Setting of sight to give correct direction; neces- sary in both direct and indirect laying. Deflection difference. — Correction applied with indirect lay- ing to make the deflection applicable to the pieces other than the one for which it was determined. Site. — The angular elevation of the target with respect to the piece, used only with indirect laying; announced and set separately from the elevation, or included in the announced ele- vation, according to materiel and method. Projectile, charge, fuse. — Generally speaking, matters of selection rather than determination; must be announced however. Fuse setting. — Necessary in time fire only. Method of fire. — Discussed later. Range or elevation. — Necessary in both direct and indirect laying. Determined range announced without change, or range setting or elevation taken from range tables, depending on ma- teriel, ammunition, and method of laying. 19. Refinements of the Preparation of Fire. — Ref- erence already has been made in several instances to details in which the preparation of fire could be refined when time and facilities permit, such as: V — 19-20 PREPARATION OF FIRE 69 The use of accurate maps for deflection and range. Topographical operations to secure more accurate data as to deflection, site, and range. Care and minuteness of instrumental measurements and cal- culations, affecting deflection, site, and range. The advantage of so doing is evident. The effect de- sired is produced more rapidly and more surely, since the accurate preparation eliminates a part of the adjustment during firing. Shortening the fire for adjustments ren- ders our artillery less exposed to neutralization or destruc- tion before accomplishing its mission. 20. Ballistic Corrections. — (a) The war gave great impetus to the practical application in the field of refine- ments in the following respects: Those related to peculiarities and irregularities of the pieces and ammunition which affect the fire; such as, weight and form of projectile, variation in powder charge, wear of the bore, etc. Atmospheric conditions; such as, the density of the air, tem- perature and its effect on the air and powder, wind. All of these matters had been studied before the war, but their practical application had been limited to the coast artillery. Their wide application in the war was possible on account of the elaborate organization and equipment of the front. Refinements of this character had the greatest tactical importance in the surprise attacks on the Western Front in 1918. (b) No detailed explanation of such corrections is possible here. It is important, however, that the combat arms with which the artillery works appreciate in a gen- eral way the disturbing elements affecting artillery fire. Those here considered are distinct from dispersion, dis- cussed later. Values are tabulated below for the 75-mm. gun at ranges of 5,000 and 10,000 meters, for the various elements stated. It is to be noted that they are for a con- crete case only, and are not generally applicable. V— 20-22 70 TACTICS AND TECHNIQUE— ARTILLERY Range Meters 1.5 inches of barometer change , due 5,000 10,000 to both temperature and pressure, will change the actual range, in me- ters, by 144 367 33 feet per second change in muzzle velocity of the piece will change the actual range, in meters, by A wind up or down the range of 22 miles per hour will cause a varia- tion from the tabular range, in me- ters, of _ _ _ 93 134 88 322 A variation of 1 lb. 10 oz. in the weight of the projectile will cause a variation in the range, in meters, of _ _ 40 132 365 955 If a combination of such influences should occur, as is possible, in such a way that their results would be cumula- tive, it can be seen that the point of fall of the projectiles would be changed by 365 meters for the range of 5,000 meters and 955 meters for the range of 10,000 meters. It is possible to correct at least partially for such con- ditions, provided the necessary meteorological and other data are available. This may or may not be the case. 21. Conclusions as to Preparation of Fire. — It may be concluded that the preparation of artillery fire requires a period of time varying from a minute to hours, depending on the situation. The artilleryman’s art consists not only of a familiarity with all methods, but also of a sensible ap- preciation of what methods are applicable in a given situa- tion, and what results can be expected. Section III Firing Over Obstacles Paragraphs Clearing the Crest 22 Reaching a Reverse Slope IIIIIIIIIIIIII 23 22. Clearing the Crest.— (a) It has been stated that protection and concealment are advantages of indirect lay- ing; in fact, they are the principal ones. The amount of V— 22 FIRING OVER OBSTACLES 71 protection afforded by a ridge behind which artillery is emplaced depends principally on the steepness of the slope in front of the position, the steeper the slope the better the protection. But if the slope is too steep, firing will be im- possible because the projectiles will not clear the crest. It is evident that the crest might be cleared for a long range or a large site, and yet not be cleared for a short range or small site. (b) A number of methods are used to determine whe- ther a crest can be cleared under given conditions, but this discussion will be limited to a single method. It has been shown that the quadrant elevation used with indirect laying is the elevation for the range increased algebraically by the site. The crest may be considered as a target, and the quadrant elevation for it found by this rule. This elevation will give a trajectory which will just clear the crest. By comparing this quadrant elevation with that for the target, it can be seen at once whether fire on the target will clear the crest. To clear the crest , the quad- rant elevation for the target must exceed that for the crest. It is to be noted that the addition of the elevation for the range of the crest and the site of the crest always will be an arithmetical one, since from its nature the crest will be above the pieces and its site plus. The site of the tar- get however must be considered carefully as to sign. The following examples illustrate the method: (1) Site of target, minus, 12 mils; range of target, 6000 meters. The pieces are in position 500 meters behind a crest whose site is 270 mils. Can the crest be cleared with 75-mm. shrapnel fire? With shell fire? Solution : Shrapnel . — The elevation for the range of the tar- get is, from the range tables, 269 mils. The quadrant elevation for the target then is 269-12=257 mils. The elevation for the range of the crest is 10 mils ; the quad- rant elevation for the crest, 280 mils. Since the quadrant elevation for the target does not exceed that for the crest, the crest will not be cleared. Shell . — The quadrant elevation for the target is 290 mils. This exceeds that for the crest, so that the crest will be cleared. (2) A certain battery position has been selected tentatively from the map, on the eastern slope of Sentinel Hill on the 900- foot contour. What is the minimum range which could be used with 75-mm. shell, firing west over the hill? Assume the site of target as 0, and the height of the trees on the hill as 30 feet. Solution : Judged from the contours, the shoulder on the V — 22-24 72 TACTICS AND TECHNIQUE— ARTILLERY slope is about on the 1000-foot contour. The distance between the 900 and 1000-foot contours is 200 yards, or 600 feet. The vertical interval, including the trees, is 130 feet. The slope of the “crest” is then 130/600=21.7%. 21.7x#=12.4 degrees, or the slope is about 12° 24'.* In addition, it is well to allow about 30' clearance to cover inaccuracy and irregularities on the hill. The elevation for the range of the crest is about 12'. The per- missible quadrant elevation is then 12° 24' plus 30' plus 12' = 13° 6'. Since the site of the target is 0, 13° 6' is the permissible ele- vation for the range of the target. The required minimum range is, from the tables, about 5200 meters.f 23. Beaching a Reverse Slope. — Ground protected from hostile fire by a covering crest can be reached if the angle of fall of the fire directed upon it is sufficiently great. The vulnerability of terrain to fire in this manner may be determined with sufficient accuracy by comparing the re- verse slope with the angle of fall of the trajectory. The latter is given in the range tables, or may be taken roughly as one-half greater than the elevation. The slope of the terrain may be determined from the map, or the scale of slope equivalent may be used. The problem may be solved also by the method of clearing the crest, already described. Section IV Ballistics Paragraphs Defined 24 Trajectory 25 Nomenclature of Trajectory 26 Drift 27 Jump 28 Effect of Muzzle Velocity and Elevation on Range 29 Rigidity of the Trajectory 30 Atmospheric Conditions 31 24. Defined. — Ballistics treats of the motion of pro- jectiles fired from cannon or small arms. The subject may * Empirically, the slope in % x % = slope in degrees. The mil re- lation is rather inaccurate for large angles. In mils, this slope would be 217. 200 mils=732 minutes = 12° 12'. The accurate value of the slope is 12° 16'. fThe use of the slope in per cent and the degree units in this problem is merely illustrative. It would be more convenient and simpler to use mils throughout. Both methods give substantially the same result. V— 24-25 BALLISTICS 73 be divided into three branches; interior ballistics , treating of the motion of the projectile within the bore; exterior ballistics , treating of the motion of the projectile after leav- ing the bore and during its flight; and a third category* termed the ballistics of 'penetration , treating of the effect of the projectile on the object it strikes. This brief discussion will be confined to exterior bal- listics. 25. Trajectory. — The trajectory is the path followed by the projectile in its flight. The trajectory is determined by the angle of departure (almost the same as elevation), the muzzle velocity of the projectile, and the characteris- tics of the projectile. If the force of gravity, the resistance of the air, and the rotation of the projectile about its axis could be eliminated, the projectile would describe a straight line determined by the line of departure; its velocity would remain constant. The force of gravity causes the projectile to drop away from the line of departure. Neglecting the resistance of the air, and considering only the angle of departure, the muzzle velocity, and the force of gravity, the trajectory would be a parabola, with the highest point at midrange, and with the two halves identical in shape. Such a trajectory is known as the trajectory in vacuo. The resistance of the air acts to retard the projectile, and from the instant the projectile leaves the bore tends continuously to reduce the velocity. As a result, the highest point of the trajectory in air is nearer the point of fall, and the ascending and descending branches are unequal and un~ symmetrical. Figure 6 is a comparison of the trajectory in air with that in vacuo for the 3-inch gun. The angle of Figure 6. — Trajectories in air and in vacuo V— 25-29 74 TACTICS AND TECHNIQUE— ARTILLERY departure is that for a range of 5000 yards in air. The vertical scale has been doubled in the figure. 26. Nomenclature of Trajectory. — Figure 7 shows the nomenclature of the principal elements of the trajec- tory. 27. Drift. — The rotation imparted to the projectile by the rifling of the bore, together with the resistance of the air, causes the projectile to deviate from the plane of fire. This deviation is called drift. The rifling of all field artil- lery has a right hand twist, and consequently the drift is always to the right. 28. Jump. — The angle of departure differs from the ele- vation at which the piece is laid by such derangement of the laying as takes place while the projectile is moving through the bore. This angular difference is called the jump. The jump is upward or positive when the angle of departure is greater than the elevation. The jump is given in the various service range tables; it is positive for most types of artillery. 29. Effect of Muzzle Velocity and Elevation on Range. — (a) For the same projectile and elevation, the V— 29 BALLISTICS 75 greater the muzzle velocity, the greater the range. The practical limitation on muzzle velocity is the weight of the materiel, as well as the fact that the wear of the bore is great for high velocities. Up to a certain elevation, about 45 degrees*, the range increases with the elevation; for greater elevations, the range decreases. This is shown in Figure 8. (b) The various types of field artillery may be classi- fied in this respect as follows : (1) Guns, having relatively high muzzle velocity and a more or less limited maximum elevation. (2) Howitzers and mortars , having relatively low muzzle velocity but capable of firing at high elevation. *The German long range gun is of interest in this connection. It will be remembered that 7 of these guns were built, of 21 cm. (8.15") caliber except that probably one was of 24 cm. (9.3") caliber. They bombarded Paris on 44 days, killing 256 and wounding 620 persons. 303 projectiles were fired, 183 falling inside of the walls and 120 out- side. The guns were 121 feet long; the life was about 50 rounds; they were mounted on railway carriages. The extreme range was 76 miles, the trajectory reaching a maximum height of 24 miles. The elevation for this range was 55 degrees. The projectile weighed 264 lbs., was 41i inches long, and had a muzzle velocity of 5090 feet per second. The time of flight for extreme range was about 3 minutes. Figure 8 V — 29-30 76 TACTICS AND TECHNIQUE— ARTILLERY (c) For a given caliber, the gun would have the great- est weight of materiel and the greatest range, with the how- itzer and mortar next in the order named. For a given weight of materiel, the gun would have the smallest cali- ber, greatest velocity, and longest range ; the mortar would have the largest caliber, least velocity, and shortest range ; the howitzer would be between the gun and the mortar in these characteristics. In addition, the mortar has the dis- tinctive feature that it fires only at elevations greater than 45 degrees, so that its range decreases as the eleva- tion increases. The gun and howitzer classification is a comparative one, and not based on rigid numerical values. Guns are being made today that can be elevated to 45 de- grees, and modern howitzers have muzzle velocities that formerly might have placed them in the gun class. The anti-aircraft gun is a gun properly speaking, because of its high velocity ; yet it can be elevated to 90 degrees, an eleva- tion formerly characteristic of mortars. The mountain howitzer, having a muzzle velocity of about 900 feet per second, formerly was classed as a gun. (d) The dominant characteristic of the gun is its long range ; of the howitzer, its high angle of fall with considera- ble range; of the mortar, its extreme angle of fall with short range. BO. Rigidity of the Trajectory. — (a) The range tables are computed, stricty speaking, for horizontal planes of site. This obviously is rarely the case in the field. In order to simplify the mechanism and methods of field ar- tillery firing, use is made of what is known as the principle of the rigidity of the trajectory. (b) The principle of the rigidity of the trajectory is the assumption that the relations existing between the ele- ments of the trajectory and the chord representing the range are the same whether the chord be horizontal or in- clined. In other words, a trajectory remains rigid as to form and extent while it and its chord are revolved in a vertical plane about the origin or muzzle as a center, through the relatively small angles involved in practice. V — 30-31 BALLISTICS 77 Figure 9. — Rigidity of Trajectory (c) In Figure 9 three planes of site are shown, GP a , GP h , and GP b . P a , P b , and P b are all the same distance from G. P h will be reached by a trajectory whose elevation above GP h is E h , which value may be obtained from the range ta- bles. By the principle of the rigidity of the trajectory, if the piece be elevated above GP a by the same amount E h , the trajectory will reach P a ; and if the piece be elevated by E h above GP b , the trajectory will reach P b . (d) The principle is applied in both direct and indi- rect laying. (e) The determination of the range of the horizontal trajectory which would pass through an elevated or de- pressed target ordinarily would be impracticable in service, so that, the application of the principle greatly simplifies the practical operation of laying for elevation. The differ- ence between the horizontal and inclined ranges is consider- able only when the elevation is great and the site is what may be considered as extreme. Nevertheless, correction sometimes is made for it, the necessary data being contained in the service range tables. 31. Atmospheric Conditions. — (a) The range of the projectile and the burning of the powder train in the time fuse are influenced by the atmospheric temperature, baro- metric pressure, and movement (wind). Moisture in the air (humidity) has a negligible effect. V — 31-32 78 TACTICS AND TECHNIQUE— ARTILLERY (b) For a constant barometer, the lower the tempera- ture the shorter the range ; the higher the temperature, the longer the range. For a constant temperature, the lower the atmospheric pressure or barometer, the longer the range ; the higher the pressure, the shorter the range. In a high altitude, where the pressure is low, the range is long. (c) In summer, when the temperature is high and the barometer low, the range is long; in winter, when the tem- perature is low and the barometer high, the range is short. (d) The lower the temperature, the more slowly the time train of the fuse burns; the higher the temperature, the more rapidly it burns. The lower the pressure, the more slowly the time train burns; the higher the pressure, the more rapidly it burns. (e) A wind behind the projectile increases the range; a head wind has the opposite effect. (f) When a battery commander is furnished meteoro- logical data, he can correct his firing data accordingly by means of the service range tables. Section V Dispersion — Probability Paragraphs General 32 Defined 33 General Effects of Dispersion 34 Nature of Dispersion 35 Dispersion on Sloping Ground 36 Safety of Friendly Troops Due to Dispersion 37 Probable Error 38 Probability 39 32. General. — In the preparation of fire, sufficient de- tails were given to show the unavoidable approximations and many uncertain elements entering into the problem, and make it evident that the preparation of fire in the general case must be imperfect. Imperfections are not confined to the preparation of fire, but enter into the firing itself, not- ably because of dispersion. y— 33 DISPERSION— PROBABILITY 79 33. Defined. — Dispersion as applied to firing is the scattering of shots intended to strike or burst in the same place. Shots fired with the same data and ammunition Zone c o 0< o o O iuo / 0 OO O >o O ° o □O rx~of 1 °8\ pcgoo O&j »®o e0% <%<*> 7n « oofi Ago 70/0 jQCt 0U70 3Vyo a Aft/ iK> Center of O Cafe; rTcSg ■ uuiurn / 1/ 7c? o a cst- SBoX /a QSfph 0O70 ' 7^70 5.0% od| ©O' O Tfll Art Ool °8°J 4jo6 • 10 70 PofP ptnof. 0 o cn °o1 °J ° 1 ° J ° A n ^ 7 * o° 0 0 >0 0 >°o ^°° r 0 nO lOO 0 !* Figure 10 — Dispersion V — 33-35 80 TACTICS AND TECHNIQUE— ARTILLERY should strike in the same place, but it is well known that such is never the case. Figure 10 shows the results ob- tained from firing 400 shots from the same gun under as nearly as possible the same conditions. The longer dimen- sion of the pattern is in the direction of range ; the shorter dimension, laterally. 34. General Effects of Dispersion. — D ispersion is a practical factor in several respects. (a) It decreases the hits on a target of limited extent. (b) It decreases the effectiveness of the support af- forded the infantry by artillery fire, because the fire on the objective of attack must cease or lift when the infantry still is some distance away; or if the infantry approaches too close, they suffer casualties from our artillery fire. (c) It increases greatly the difficulty of conducting ar- tillery fire. 35. Nature of Dispersion. — (a) It has been estab- lished conclusively that the points of fall of a large number of supposedly like shots always will be grouped according to a fixed law, called the law of errors. The law can be ap- plied to a particular case and all desired details calculated when a characteristic value, called the probable error, is known. The probable error is tabulated in the range tables. Explanation of dispersion by what is known as the ladder of dispersion or 25-16-7-2 rule is sufficient for this discus- sion. (b) The supposedly like shots group themselves about a center , or center of impact. Consider the positions of the shots only in range. One-half are short and one-half over. Their distribution in range is shown in the longitudinal ladder of dispersion in Figure 11. (c) The parallel lines are equally spaced and one prob- able error apart. The middle line passes through the center of impact C. With the space divided in this manner, the percentages of a very large number of shots which would fall in the various spaces are those shown. These values are not strictly accurate in all cases, but are sufficiently so for practical purposes. The principal inaccuracy is in the outer or 2% spaces. The shots actually are not confined to the exterior limits shown, but the proportion outside is very DISPERSION— PROBABILITY 81 Longitudinal Ladder of Dispersion 1 Direction *-PE~* *-PEr* — 1C <~PEP> ~>OVo Zorn ‘-50% — H ? <-/?£> *-PE~* of fire *■ 2 l *25%\-2S%. m j a rqeh V 7 7°" Lateral Ladder of Dispersion -JL Direction JEL ZT of fire — ZZ ££. Z r TFT- 0 s - 2 Jo 7 Jo It Jo •25 Jo V- 2 Jo Figure 11 small (7/10 of 1% for both sides of the center). The 2% spaces include all shots not included in the other spaces. (d) The lateral ladder of dispersion is constructed in a manner similar to that for the longitudinal ladder (Fig- ure 11). (e) By superimposing the longitudinal ladder of dis- persion on the lateral ladder, the shot pattern is divided into 64 rectangles as shown in Figure 12. This is called the rectangle of dispersion. ^ PE PE -> PE —* <- PE-> PE PE v- PE «- PE~> 3*. s PE *7% T ~PE 4V. * P£ 1 1 Erjs, i/on of Ft re 6-25% . 6 25’/, T ~p£ *2£*J 6. 25'/. ‘ 6.25 V, ~*pe & 4V- 4 V, \-fpk jzL -*Tpe 1 T 7 * ! 1 7% -5> 2.S 7* <- 25% ^ * 16% +- 7%-f- <~2% -* Figure 12. — Rectangle of dispersion (PE stands for “probable error’') The percentages for the various rectangles are obtained by multiplication of the appropriate longitudinal and lat- V — 35-38 82 TACTICS AND TECHNIQUE— ARTILLERY eral percentages; for example, 6.25% is the product of 25% and 25%, 4% is the product of 25% and 16% etc. The to- tal of the percentages for all rectangles is of course 100, since all of the shots are assumed to fall somewhere within the rectangle of dispersion. 36. Dispersion on Sloping Ground. — The tabular values of the range probable error are for horizontal ground. If the ground on which the shots fall slopes downward away from the piece, as on the reverse slope, the dispersion is greater than on horizontal ground ; if the ground were paral- lel to the descending branch of the trajectory, the disper- sion would be indefinitely great. If the ground slopes down- ward toward the piece, as on a forward slope, the disper- sion is less than on horizontal ground, the minimum being when the ground is perpendicular to the trajectory at the point of fall. The probable error for sloping ground may be obtained by projecting the horizontal value onto the slope by means of the trajectory. 37. Safety of Friendly Troops Due to Dispersion. — For horizontal ground it generally is taken that friendly infantry cannot approach more closely than the following distances to the center of impact of fire of the 75-mm. gun in the direction of range, that is, when the fire is over their heads : Percussion shell or time shrapnel, depending on the range : 150 to 200 yards. Time shell 200 to 250 yards. This takes into consideration not only the dispersion of the trajectory, but also the effective radius of the frag- ments, and, in time fire, the dispersion of the fuse in time of burning. For the 155-mm. howitzer, the distance is 500 yards. With the 75-mm. gun firing in enfilade, the distance may be reduced to about 75 yards. For ground sloping downward away from our lines (re- verse slope), the safe distances are greater; such ground is dangerous for friendly troops, and precautions should be taken to guard against losses. For ground sloping down- ward toward our lines, the safe distances are less. 38. Probable Error. — (a) ‘The tabular values of the probable error constitute a measure of the relative accur- V— 38-39 DISPERSION— PROBABILITY 83 acy of the pieces ; a small probable error indicates an accur- ate piece. (b) It will be noted that the probable error increases with the range, and very rapidly at extreme ranges ; so that the accuracy decreases with the range. The accuracy in direction is much greater than in range; hence, from this viewpoint, it is desirable to attack a target so that the direc- tion of fire will be along the greatest dimension of the tar- get ; for example, a trench should be enfiladed. (c) As between a gun and a howitzer of comparable characteristics, the howitzer is generally more accurate in range, principally on account of its greater angle of fall. The reason is analogous to the case of dispersion on ground sloping downward toward our lines. There are however some factors that tend to make the gun more accurate. (d) The tabular probable errors* are obtained by ex- perimental firing at the proving ground, with extreme care in laying and favorable atmospheric conditions. In service, conditions usually are less favorable; it is therefore cus- tomary to increase the tabular probable errors by 50% in using them practically. The probable error varies with conditions ; it is greater in a rapidly fluctuating wind, when the piece is worn, or when the ammunition is old. 39. Probability. — (a) Probability is applicable to events involving uncertainty, and furnishes a numerical measure of our reasonable expectations based on an incom- plete knowledge. Since most artillery problems involve some degree of error or uncertainty, there is a wide field for the application of probability in many forms, most of which cannot be taken up here. (b) One of the commonest applications of probability is in connection with hitting a target. Two illustrations will be given. (1) Assume a target 20 meters in range by 15 meters later- ally. The fire has been adjusted correctly for direction, that is, the center of impact is in the direction of the center of the target; but the center is 25 meters short of the nearest element of the target. The piece is a 75-mm. gun firing shell at a range of 6000 meters. *It is contemplated that future range tables shall give probable errors which are 50% greater than the proving ground values. These values will be called the field probable error . V— 39 84 TACTICS AND TECHNIQUE— ARTILLERY What is the probability that the next shot fired will hit the target? Solution'. The desired probability is the percentage of hits that would be obtained out of a large number of shots. Such shots would be grouped around the center in accordance with the ladder of dispersion. The tabular probable error, plus 50%, is 33 meters for range and 6 meters for deflection. First neglect lateral dispersion and consider the target as of indefinite extent laterally. It extends 33 — 25 = 8 meters into the 25% space. Therefore %s of the 25% of the shots falling in this space would be hits, or 6.06%. Similarly the target ex- tends 20 — 8 = 12 meters into the 16% space, so that of the 16% of shots falling in this space would be hits, or 5.81%. The total percentage of hits for range then would be 6.06 plus 5.81, or 11.87%. Now neglect dispersion in range and consider the target as of indefinite extent in range. All shots falling in both 25% spaces will be hits. In addition, the target extends 7.5 — 6 = 1.5 meters in each of the 16% spaces. Therefore l.% of the 16% of shots falling in each of these spaces will be hits, or 4% for each space; or 8% for both spaces. The total percentage of hits for direction then would be 50 plus 8, or 58%. Since 11.87% of shots are hits for range and 58% are hits for direction, the percentage that will be hits for both range and direction 11.87% x 59% = 6.9%, which is the probability sought. In other words, the chance of the next shot hitting is about 1 in 15. More precise methods, involving the use of the probability table, give a value of 7.5% instead of 6.9%. (2) An attack is preceded by a rolling barrage of shells fired by 75-mm. guns. The first infantry wave is 100 meters behind the centers of impact. What is the probability of a shell falling among friendly infantry when the guns are firing at 4000 meters? When they are firing at 8000 meters? Solution’. 4000 meters. The desired probability is the per- centage of short shots of a large number such as the one con- sidered. The field probable error in range is 22.5 meters. 4 probable errors is only 90 meters, so that the percentage of short shots is negligibly small, and the required probability is practically 0. 8000 meters. The probable error in range is 58.5 meters. 100 meters (the distance the infantry is behind the center of im- pact) includes the 25% space and 41.5 meters of the 16% space. Therefore 41.5/58.5 of the 16% space would receive safe shots, or 11.4%. All shots beyond the center would be safe. Therefore the percentage of safe shots would be the sum of 50, 25, and 11.4, or 86.4. The remainder would be short shots, and the required probability is 100 — 86.4 = 13.6%. In other words, 1 shot in 7 would fall among the friendly infantry. (c) The second example shows the increased danger to friendly troops due to the use of long ranges by the artil- lery. From a comparison of the results with the data given in paragraph 37, it may appear that the data given are un- necessarily conservative, but it should be noted that the example does not consider the range of effective fragments. V — 40-41 FIRING 85 Section VI Firing Paragraphs Subdivisions of Firing 40 Observation 41 Methods of Adjustment 42 Adjustment by Measured Deviations I 43 Adjustment by Bracketing 44 Adjustment of Time Fire 45 Method of Fire During Adjustment 46 Fire for Effect 47 Registration 48 Barrages 49 40. Subdivisions of Firing. — (a) As brought out in paragraph 19, it is desirable to make the preparation of lire as accurate as possible, but it always is found necessary to make corrections during the firing in order to secure the maximum effectiveness. This is in general possible if the firing can be observed, and the period of firing devoted to this purpose is called fire for adjustment. When the ad- justment has been completed as far as circumstances per- mit, fire for effect is or may be undertaken. If observation is not possible, fire for effect is delivered from the outset, but with diminished effectiveness. No amount of careful preparation of fire can eliminate the necessity of fire for adjustment, or yield the same effectiveness. (b) There is no clear line of demarcation between fire for adjustment and fire for effect; considerable effect may be obtained during adjustment, and adjustment is continued if necessary during fire for effect. During adjustment how- ever, effect is a secondary consideration; while during fire for effect, effect is the principal object. 41. Observation. — (a) Observation, on which fire ad- justment depends, is viewing the strike of the projectiles in order to determine their location with respect to the tar- get. Observation is of two kinds, terrestrial and aerial. The latter will be discussed later. (b) Terrestrial observation is classified, according to the position of the observer with respect to the line of fire, as : axial, when the observer is on or near the line of fire ; V — 41-43 86 TACTICS AND TECHNIQUE— ARTILLERY lateral, when he is considerably displaced from the line of fire ; flank, when he is on or nearly on the flank of the target ; combined, when one axial observer and one lateral or flank observer are used conjointly; and bilateral, when two or more lateral or flank observers are used conjointly from considerably separated points. (c) A single observer near the line of fire can deter- mine the angular deviation of the shot in direction, that is, its angular distance from the target. In range, ordinarily he can determine only that the shot is short or over, that is, he can sense it; but he cannot determine the deviation in range. The sensing is by means of the smoke of the burst; if it hides the target, the shot is short ; if it brings the tar- get into relief, the shot is over. If the observer is directly to one flank of the target, he can determine the angular deviation in range, but cannot do no more than sense the shot in direction as right or left. (d) The use of combined observation under favorable conditions may permit the determination of the deviation of the shot in both range and direction. 42. Methods of Adjustment. — There are two methods of adjustment employed, depending on whether the system of observation of fire is such that the deviation in both range and direction can or cannot be determined. (a) Adjustment by measured deviations, sometimes called the method of successive approximations, used when the deviation of the shot in range and direction can be de- termined accurately. (b) Adjustment by bracketing , used when the method by measured deviations is not practicable. The bracketing method is the usual one in field artil- lery firing; that by measured deviations, the exceptional one. 43. Adjustment by Measured Deviations. — (a) The actual first shot is disregarded, or numbered 0, as it is apt to give misleading results. The first shot, so-called, is fired with the same data. The second shot is fired with data corrected by the deviations of the first shot, and should hit the target; but in general it does not, due to dispersion. The third shot is fired with data corrected by one-half the V — 43-44 FIRING 87 deviations of the second shot. Similarly the deviations of the third shot are divided by three for application to the fourth shot, and so on till the adjustment is sufficiently refined. It is seen that the method consists in dividing the deviations for a shot by the number of the shot, as a basis of correcting for the succeeding shot. This gives due weight to the results of all shots fired and should insure a steady approach to the target. If the adjustment is not satisfac- tory after the sixth shot, it is taken as an indication that some of the deviations have been erroneous and the adjust- ment is begun anew. (b) Unfortunately the measured deviations essential to this method are rarely available, and its application is limited to highly organized fronts. It is to be noted that dispersion makes its influence felt in this method by pro- tracting and complicating the process. 44. Adjustment by Bracketing. — (a) The observer usually is near the line of fire. Fire is opened with the de- termined data. The direction then is corrected by the measured deviation. If the observation for range is “short” the range is increased; if “over” the range is decreased. The amount of the range change depends on the accuracy of the initial determination ; if we were very confident of its accuracy, about 100 meters would be sufficient; but if the initial range was estimated and rather long, a change of 400 meters might be advisable. One or more shots are fired at the altered range; and if still in the same sense as the first range, the range is changed again by the same amount. Finally a range will be found which gives shots in the opposite sense. Thus there will be two ranges, differing by 100, 200, or 400 meters, or by a substantially equivalent amount in elevation, one range giving observations short and the other observation over. These two ranges consti- tute what is called a bracket. (b) It would seem that a bracket based on correctly observed shots would make it certain that the target lay within the ranges of the bracket. This would be true but for one factor — dispersion. If one shot is observed at say the short limit of the bracket, the shot may be one at the short limit of the dispersion. In this case, although the V — 44-45 88 TACTICS AND TECHNIQUE— ARTILLERY shot actually is short, the center of impact and the range may be over, which raises doubt as to the correctness of the bracket. For this reason, it is good practice to verify a bracket, before finally accepting it, by securing at least two observations at each limit. (c) After obtaining the first bracket, the process of range adjustment is continued by firing at the mid-range of the bracket. When this range has been observed, a new bracket results of one-half the size of the former one. This process is continued until a further reduction would make the bracket smaller than the target, or until the bracket is of a size equal to four field probable errors, approximately 100 to 200 meters, generally near the lesser value. This process is called a bracket adjustment. (d) If a more accurate adjustment is necessary, and time permits, as for the destruction of a small target like a battery or trench, a precision adjustment is undertaken. Fire is opened at the mid-range of the last bracket obtained, that is, one of six tabular probable errors. This range al- most surely will give both shorts and overs. Based on the proportions of shorts and overs, small changes of range or elevation are made until substantially equal proportions of shorts and overs are obtained. If, during the early stages of bracketing, a range gives both shorts and overs, the precision adjustment may be undertaken at once. (e) If the observer, instead of being near the line of fire, is to the flank of the target, adjustment for range is by measured deviations and that for direction is by bracket- ing. 45. Adjustment of Time Fire. — Time fire may be with either shrapnel or shell. Shrapnel adjustment consists of the adjustment of the trajectory as just described, fol- lowed or accompanied by an adjustment of the fuse so that the projectile will burst in air at the proper height. This height depends on the weapon. For the 75-mm. gun, the best height of burst in fire for effect is 3 mils above the target, with the trajectory pass- ing through the target. With time shell fire, the object is to place the burst vertically above the target, at a linear height of about 20 V — 45-47 FIRING 89 yards. The methods are different from those used with time shrapnel. 46. Method of Fire During Adjustment. — The usual method of fire during adjustment is the salvo, and generally by the entire battery. A salvo is the successive discharge of the pieces at regular intervals from one flank of the bat- tery to the other. The interval is about 3 seconds. The object of the interval between shots is to permit the obser- vation of individual shots, in order that all possible infor- mation may be derived from them. Salvos may be platoon or battery, depending on whether two or four pieces are used. In precision adjustment, the pieces sometimes are ad- justed separately. 47. Fire for Effect. — (a) Fire for effect is of three classes, depending on the extent of the preceding adjust- ment. (1) That based on a precision adjustment called precision fire for effect. This is simply a continuation of the last stage of adjustment. Successive salvos are fired at the range or eleva- vation determined in adjustment. Firing is continued until the desired effect is obtained or until a large accumulation of obser- vations show that the range is incorrect. In the latter case, which generally would be due to atmospheric conditions, a suita- ble change in elevation is made and the firing continued. (2) That based on a bracket adjustment. The entire depth of the bracket and width of the target are searched with a thoroughness depending on the time and ammunition available and the importance of the target. Usually the range is changed by bounds of 25 or 50 meters for shell and 100 meters for time shrapnel. It is desirable to use bounds in direction of 10 meters for the 75-mm. gun and 20 meters for the 155-mm. howitzer. The method of fire used may be battery volleys, in which each piece fires rapidly a prescribed number of rounds with fixed data, but without regard to the other pieces. (3) That based merely on the preparation of fire, without previous adjustment called systematic fire for effect. It was this method which was used so extensively on the Western Front, since the consideration of secrecy Drevented practically all fire for ad- justment. (b) The methods of zone and systematic fire for effect, particularly the latter, are extravagant in ammunition, and relatively ineffective. The lack of concentrated effect must be offset by increasing the amount of artillery firing on a given locality ; the rate of fire is limited by the resistance of the materiel. These methods are useful principally for neu- tralizing, that is, causing the enemy to take cover, and keeping down or stopping his fire. V — 47-49 90 TACTICS AND TECHNIQUE— ARTILLERY (c) Precision fire for effect is the only method which can be relied upon for considerable and thorough destruc- tion. 48. Registration. — (a) Adjusted fire can be delivered on a target without adjustment on the target itself, particu- larly when good maps are available. A distinctive point, called the datum or registration point, is selected in the vicinity of the target, and a precision adjustment made upon it at leisure. The fire then is shifted to the target by meas- uring the difference in data between the datum point and the target, either from the map or on the ground. (b) The use of a datum point may be necessary either because observation on the target is not possible or because the target has not yet appeared. This method of registra- tion is effective in preparing to attack prospective targets quickly, but it may reveal prematurely the presence of the artillery. 49. Barrages. — (a) Barrages are a form of fire for effect, in that they are prepared or adjusted beforehand and effect is the primary consideration while they are being de- livered. (b) In a defensive or standing barrage in a stabilized situation, a 75-mm. gun battery generally covers a front of 200 meters or, desirably, less. This front is divided into four portions, each assigned to one gun. Each gun fires initially at the right extremity of its portion; the succeed- ing shots are distributed to the left of the first shot at in- tervals of about 15 meters until the allotted portion is cov- ered, when the sweep is repeated. Such barrages must be fired immediately on call from the infantry, so that the pieces are kept laid constantly for the normal barrage. A sentinel is on duty at each gun emplacement night and day with orders as to just how the barrage is to be fired and with what data. The ammunition, habitually shell, is piled by the piece ready for use. The firing data are corrected periodically for weather conditions where the necessary meteorological data are available. (c) Similar detailed preparatory measures are taken in the case of the other emergency missions, such as possible barrages and counter preparations. V — 49-51 AERIAL OBSERVATION 91 (d) The rolling barrage is prepared initially in much the same detail as the standing barrage, with additional detailed provisions for its progression according to a fixed time schedule. Ordinarily each piece is supplied with a form sheet filled in under the following headings: the H time, giving the time at which fire is opened at each of the suc- cessive elevations referred to H hour; the synchronized time, filled in after H hour is announced ; the site, varying if necessary with the terrain; the kind and lot of ammuni- tion and fuse ; the elevations ; the method of fire and num- ber of rounds at each elevation ; the rate of fire. The forms are filled in progressively as the data become available, the last elements usually being the synchronized times and the deflections and elevations corrected for the meteorological data received just before the firing. (e) The great amount of ammunition expended in fir- ing either a standing or a rolling barrage should be appre- ciated by all officers. For a standing barrage, with an aver- age rate of fire and an average duration, the expenditure for 75-mm. guns is about 28 rounds per gun each time the barrage is put down. For a rolling barrage, with an aver- age rate of fire and an average rate of advance, the expendi- ture may be taken as one day of fire (300 rounds) for each 75-mm. gun, for each 2500 yards’ advance. Section VII Aerial Observation Paragraphs General 50 Balloon Observation 51 Airplane Observation 52 50. General. — Aerial observation is of two kinds, bal- loon and airplane. Both have decided advantages over ter- restrial observation in the greater amount of hostile terrain vissible. 51. Balloon Observation. — The methods of balloon observation are essentially those used on the ground. Com- V— 51-52 92 TACTICS AND TECHNIQUE— ARTILLERY munication is normally by telephone direct to the battalion or battery firing. 52. Airplane Observation. — (a) An airplane has the advantage of practically vertical observation, which is val- uable not only in the observation of fire but also in the loca- tion of targets. The deviation of the shots can be deter- mined in both range and direction, at least as far as the position of the observer is concerned (par. 41). The dis- advantages of airplane observation of fire are in communi- cation with the ground, the movement of the plane, the ob- struction of vision for various reasons, and the operations of hostile planes. In addition, a high degree of cooperation between the airplane and the artillery is necessary and is difficult of attainment. (b) Communication between the airplane and the ground is now by radio; it was formerly by visual signal, and developments point to the use of the radio telephone for the future. Communication between the ground and the airplane is ordinarily by panel signals displayed on the ground, but some airplanes are now equipped with facilities for receiving radio, in which case reciprocal radio communi- cation is possible. Codes are used ; messages rarely can be spelled out, as it would require too much time. (c) The observer can estimate distances in connection with the burst of shots by comparison with known distances between prominent points, or he may use a gridded map or photograph. When the shots are close to the target (about 100 yards in range or 10 yards in direction), the observer reports only the sense, as, short or over, right or left. (d) The methods of adjustment and fire for effect are those described in connection with terrestrial observation. Adjustment by measured deviations (par. 43) sometimes can be used, when the observer can estimate the deviations with sufficient accuracy. The preparation should be as ac- curate as possible. In addition, if the battery has oppor- tunity to adjust partially, the first shots are less apt to be lost by the aerial observer and the adjustment will be expe- dited. (e) Airplane observation at night is possible, under special conditions. VI— 1-2 CHAPTER VI Reconnaissance. Selection of Positions Paragraphs Section I. — Reconnaissance 1-10 Section II. — Selection of Positions 11-26 Section I Reconnaissance Paragraphs Reconnaissance for Positions 1 Reconnaissance for Information 2 The General Selection of Artillery Positions 3 The Progression of Artillery Reconnaissance 4 Additional Reconnaissance Required 5 Conveyances for Reconnaissance 6 Instructions to Artillery Units During a Reconnaissance — 7 Time Available for Artillery Reconnaissance 8 Transmission of Information During a Reconnaissance 9 Reconnaissance by Heavy Artillery 10 1. Reconnaissance for Positions. — (a) Reconnais- sance for positions is greatly aided by familiarity with the terrain. It is, therefore, essential that artillery officers con- stantly study the topography and compare the terrain fea- tures with available topographical maps. An “eye for the ground” is one of the principal requisites of an artillery officer. (b) Invariably a reconnaissance is made for the pur- pose of locating suitable positions for artillery units, and the actual sites for battery emplacements, or the emplace- ments for platoons or individual guns. Co-related with this reconnaissance is that made for the locations of suitable sites for observation posts, command posts, and radio sta- tions, of suitable positions for limbers and combat trains, of routes of approach and supply, and of routes for laying tele- phone lines. 2. Reconnaissance for Information. — (a) In gen- eral, reconnaissance for locating the enemy and gaining in- 93 94 TACTICS AND TECHNIQUE— ARTILLERY formation concerning him devolves upon troops of other arms. Successful artillery support depends in a great measure upon the prompt transmission of such information to the artillery. Artillery commanders employ every means in their power to establish such relations with commanders of other arms as to insure prompt transmission of informa- tion. Quick and reliable communications are essential, as well as an efficient information service in the artillery com- mand for gathering and disseminating the information ob- tained. The artillery information service is discussed in Chapter XVIII. (b) Though depending to a large extent upon other arms for information concerning the enemy and the tactical situation, there are certain types of information that must be gathered by means of artillery reconnaissance. Artillery liaison officers accompany the commanders of supported in- fantry and cavalry units in both offensive and defensive action, in order to keep the artillery commanders informed as to changes in the tactical situation, and as to the coop- eration desired of the artillery by the other arms. These liaison officers usually have reconnaissance detachments (scouts) that search for special information of tactical and technical value to the artillery command to which they be- long, such as the effect of both hostile and friendly artillery fire, the description and coordinates of suitable artillery tar- gets, the location of forward observation posts, routes of ad- vance, battery positions, and places where the assistance of engineers will be required for the advance of artillery. (c) In addition to these reconnaissance parties closely associated with the other arms, there must be reconnais- sance parties with independent artillery missions, such as those sent out by battalion and higher commanders for the reconnaissance of routes and positions or to gain some spe- cial information, those accompanying raids to gain informa- tion within the hostile lines, and those sent forward by bat- tery commanders to seek observation close to the front lines, in order that the effect of fire may be observed, targets lo- cated, or fire conducted on targets that cannot be seen from observation posts nearer the firing batteries. YI— 2-4 RECONNAISSANCE 95 (d) Active reconnaissance is essential to artillery ef- ficiency. An artillery command must find most of its own targets and determine the necessary technical information concerning them; it cannot depend upon the troops it is supporting to tell it constantly when, where and how to employ its fire. 3. The General Selection of Artillery Positions. — (a) The tactical situation and the plan of action decided upon by the commander of the troops limit the areas with- in which artillery takes position. The artillery is, there- fore, not usually free to choose its owm locations, but makes the best use of the terrain within the limits imposed. (b) After considering the recommendations of his ar- tillery advisor, the commander of the troops designates the areas within which, or places near which, the artillery is to take up its positions, and influences the distribution of units by a general indication of the tasks to be performed. 4. The Progression of Artillery Keconnaissance. — (a) Our field artillery drill and service regulations require that “all field artillery commanders habitually precede their commands to the position to be occupied.” (b) The artillery advisor or the senior artillery com- mander should be in close touch with the commander of the troops, and should accompany him on his preliminary re- connaissance. In this way he is kept informed as to the tac- tical situation and plan of action, and receives early instruc- tions as to the special tasks to be performed by the artillery. During this reconnaissance, and in accordance with the in- structions he receives, he formulates a plan for the disposi- tion and employment of the artillery. At the earliest op- portunity he communicates this plan to the next subordinate artillery commanders. Depending upon the situation and the time available, this plan is communicated by means of a written order, or verbally to his next subordinates, who either accompany him on a reconnaissance or meet him at a designated rendezvous point. Thus commences a pro- gression of reconnaissances that extend successively from each artillery commander to those of the next lower units. (c) In large commands this progressive reconnaissance is made : first, by brigade commanders to determine suitable VI— 4-6 96 TACTICS AND TECHNIQUE— ARTILLERY areas, within the limits imposed by the commander of the troops, for the employment of their regiments; second, by regimental commanders to select the general locations for battalion positions; third, a more detailed reconnaissance by battalion commanders to locate, within narrow limits, the position for their batteries ; and, last of all, a reconnais- sance by battery commanders to determine the exact posi- tions for the guns. These various steps, in the reconnais- sance for the selection of artillery positions, generally merge together; regimental commanders usually accompany their brigade commanders on reconnaissance, following which battalion commanders must be close at hand to receive or- ders from their regimental commanders. Battalion com- manders then go over the terrain with their battery com- manders, or if the battery commanders have not yet come up, they indicate the battery positions to the battery agents or to the battery reconnaissance officers, should the latter have accompanied the battalion commanders. (d) In some situations this progressive reconnaissance must be curtailed. There may not be sufficient time for brigade commanders to make a complete reconnaissance on the ground, and the map must be resorted to for indicating to regimental commanders the general areas to be occu- pied by the regiments. Reconnaissance on the ground is always to be preferred. 5. Additional Reconnaissance Required. — With the reconnaissance for the selection of artillery positions, dis- cussed in the preceding paragraph, there must be a sim- ultaneous reconnaissance for routes of approach, routes for lines of communications, positions for limbers and com- bat trains, and of positions for observation posts and com- mand posts. All of these factors influence, to a varying extent, the selection of artillery positions. They will be discussed in detail in succeeding paragraphs. 6. Conveyances for Reconnaissance. — A few years ago artillery reconnaissance was made on horseback or on foot. At present the automobile and motorcycle afford a means of rapid conveyance on reconnaissance that will be extensively employed in future wherever roads permit; es- pecially by the higher artillery commanders and the com- VI— 6-8 RECONNAISSANCE 97 manders of motorized units. As a rule, a thorough recon- naissance cannot be made entirely from the seat of a motor vehicle, and though a motor vehicle may provide a rapid means of transportation to the scene of a reconnaissance, much of the detailed reconnaissance must be completed on foot. 7. Instructions to Artillery Units During a Re- connaissance. — When a commander goes forward on re- connaissance he instructs the officer left in command on the following points, as far as they may be desirable or practi- cable: (1) The tactical situation; (2) whether or not the command is to follow at once, and if so the route to be fol- lowed and the rate of march. Additional instructions may be transmitted from time to time by markers, who should be left at places where uncertainty as to the route may arise or where difficulties are to be avoided. As soon as the bat- tery positions and the best routes for approaching them have been selected, the battalions or batteries are sent for and guided to their respective positions. 8. Time Available for Artillery Reconnaissance. — (a) Under some circumstances a reconnaissance may be carried on for days, as it was in preparation for the reduc- tion of the St. Mihiel Salient. Under other circumstances the reconnaissance must be completed within a few hours or even a few minutes while artillery units are marching toward the positions they are to occupy for fire. Fre- quently, it is not desirable to halt an artillery column, so that the reconnaissance must be made with great haste. It is under conditions of this kind, conditions that are fre- quently met in a moving situation, that a well-trained head- quarters with a systematized scheme of operation is of in- valuable assistance to an artillery commander. (b) When it is necessary to bring guns into action quickly for the support of other troops, delay occasioned by a protracted search for technical and tactical advantages is inadmissible. The main consideration is to place the guns as promptly as possible in a position from which they can render effective support; but even under such circum- stances, a good eye for the ground and skill in taking ad- vantage of cover, enables an artillery commander to post VI— 8-10 98 TACTICS AND TECHNIQUE— ARTILLERY his guns advantageously. As a rule, however, the necessity for the employment of artillery may be foreseen, and op- portunity may be gained for adequate reconnaissance. Ev- ery effort should be made to conclude all preparations before the arrival of the firing batteries. 9. Transmission of Information During a Recon- naissance. — Since the plan of the commander of troops is the determining factor in the selection of positions, it is essential that, during the progress of a reconnaissance, all commanders transmit to their subordinates all available information as to the plan of action and the part to be taken by their respective units; also all available information as to the location of the enemy and of friendly troops. 10. Reconnaissance by Heavy Artillery. — The re- connaissance of positions for heavy artillery commences usually with a reconnaissance of roads and an examination of bridges to determine whether or not they are strong enough for the passage of heavy guns. The engineers us- ually assist the artillery in this reconnaissance. The posi- tions for the very heavy guns depend largely upon the loca- tion of suitable roads for advancing and supplying these guns, and the availability of narrow or standard gauge track for the supply of ammunition. Section II Selection of Positions Paragraphs Tactical Considerations in the Selection of Artillery Positions 11 Tactical Classification of Artillery Positions 12 Selection of Battery Positions 13 Considerations Affecting the Selection of Battery Posi- tions 14 Considerations of Range 15 The Field of Fire and Dead Spaces 16 Considerations of Communications in the Selection of a Battery Position 17 Consideration of Observation in the Selection of Battery Positions 18 Concealment 19 Facility of Movement 20 Favorable Conditions for Resupply of Ammunition 21 Cover for Limbers or Gun Tractors 22 VI— 11-12 SELECTION OF POSITIONS 99 Gun Emplacements 23 Interference with the Operation of Other Troops 24 Security of a Battery Position 25 Protection of Guns and Personnel 26 11 . Tactical Considerations in the Selection of Artillery Positions. — The tactical situation and the plan of action decided upon by the commander of the troops, as well as the terrain, determine whether the artillery com- mand is to be massed close to the front lines or well to the rear, on either flank or in the center ; distributed along one or more lines parallel to the front or disposed in consider- able depth. The character of the terrain is a strong in- fluencing factor in the general dispositions of an artillery command. Tactical dispositions are discussed in detail in the chapters on tactical employment that follow. 12 . Tactical Classification of Artillery Positions. — (a) Artillery may be posted for immediate action, in ob- servation or in readiness . (b) When posted for immediate action the guns are unlimbered and fire is opened as promptly as possible upon indicated targets. (c) When posted in observation the guns are unlim- bered and all preparations made for opening fire at the de- sired moment upon existing or expected targets. Fire should not be opened without instructions from the com- mander who ordered a position in observation, except under circumstances that place the commander of the artillery unit out of communication, and require him to act on his own responsibility. (d) When posted in readiness, the guns are not un- limbered. They are held under cover near a position for possible immediate action, but so that they can be moved quickly to another locality if the development of the tactical situation so requires. In the meantime the immediate tac- tical situation is studied, positions in the neighborhood for posting the guns to meet different eventualities are selected, and preparations are made for occupying the selected posi- tions and for opening fire upon existing or expected targets. VI— 12-15 100 TACTICS AND TECHNIQUE— ARTILLERY (e) The use of these terms in orders is dangerous un- less their meaning is thoroughly understood by all con- cerned. 13. Selection of Battery Positions. — “The only in- variable rule in the choice of a position is to post the guns so as to be able to carry out effectively the task assigned them.” This involves consideration of range, field of fire, communications, and, in most cases, observation and con- cealment. There are also other considerations varying in importance in different situations. They are enumerated in the following paragraph. 14. Considerations Affecting the Selection of Battery Positions. — (a) Effective range. (b) Field of fire (and elimination of dead spaces). (c) Communications. (d) Observation. (e) Concealment of both the position and the approaches. (f) Facility of movement to the front, flanks and rear. (g) Favorable conditions for resupply of ammunition. (h) Proximity of good cover for limbers, or gun tractors. (i) Suitablity of the soil and the slope of the ground for “gun platforms” especially for heavy artillery. (j) Non-interference with the operations of other troops in the same vicinity. (k) Security, by the proximity of troops of other arms. (l) Possibilities for providing protection and comfort for the personnel, if the position is to be occupied during an extended period. These considerations are discussed in detail in the following paragraphs. 15. Considerations of Range. — (a) At long ranges where each increase in range requires a comparatively large increase in the elevation of the gun, there is a ma- terial decrease in the accuracy of artillery fire, and, con- sequently, in its effect. Shell may be employed effectively at greater ranges than shrapnel. To increase the maxi- mum range originally intended for the 75-mm. gun, a spec- ial shell was designed, but the protracted use of this shell, or of the heaviest propelling charges in howitzers, is very wearing on the guns, recoil mechanism and gun carriages. Consequently, very long ranges are to be avoided. (b) On the other hand, short ranges, though in most cases advantageous to howitzers, result in increased dead VI— 15-16 SELECTION OF POSITIONS 101 spaces to guns with flat trajectories. To obviate this dis- advantage for the 75-mm. gun, reduced charge ammuni- tion is manufactured, but its supply cannot always be de- pended upon, especially in moving situations. (c) Considerations of range are not only technical, but tactical as well, when considered in relation to the field of fire discussed in the next paragraph. 16. The Field of Fire and Dead Spaces. — (a) Tech- nically speaking, the field of fire of a battery includes all the ground in the direction of the enemy that can be cov- ered effectively with fire from the emplacements of the guns. Usually, when the field of fire of a battery is spoken of, it includes only that part of the battery’s possible field of fire, within which it is expected, through tactical con- siderations, to employ its fire power. This tactical field of fire usually includes a normal sector within which the battery is given its main fire missions, and an emergency sector, on one or both flanks of the normal sector, within which the battery may be assigned emergency missions. (b) In selecting a battery position, due consideration must be given to the sectors assigned, in depth as well as width. If no definite sectors have been designated, then the possible field of fire must be such as to include all pos- sible sectors that may be assigned. (c) Due to deep depressions in the terrain, or to ob- structions to the trajectories within the possible azimuth of the guns, there are usually parts of the ground within the field of fire of a battery position that cannot be reached. These are called dead spaces and because of the flat tra- jectory of guns at the shorter ranges, they are usually found comparatively close to the battery position. Dead spaces for howitzers seldom exist. (d) By the skillful selection of gun positions, dead spaces may be reduced to a minimum. Except in very open and flat country they cannot be avoided entirely. (e) So far, the discussion of the field of fire and of dead spaces, pertains to a single battery. In an artillery command the existence of dead spaces may be greatly re- duced and the field of fire enlarged by disposing the bat- VI — 16-19 102 TACTICS AND TECHNIQUE— ARTILLERY teries so that a dead space for one battery will be within the field of fire of another. 17. Considerations of Communications in the Se- lection of a Battery Position. — Communications estab- lished by a battery are usually limited to those necessary for command and for observation. When a battery is act- ing independently, additional communications are neces- sary for close connection with the supported troops of other arms. Long communications or communications that are difficult to maintain, are a distinct disadvantage. Bat- tery communications are discussed in another chapter. 18. Consideration of Observation in the Selection of Battery Positions. — (a) In spite of the innovation of map firing, high burst ranging, and adjustment by aerial observation, terrestrial observation continues to be the prin- cipal means of conducting the fire of field artillery. Even for map firing a certain amount of registration by terres- trial observation is essential to assure its effectiveness. (b) Terrestrial observation is classified and discussed in Chapter IV. Observation, in most cases, must cover ade- quately the sector or sectors assigned to the battery, and must be sufficiently close to the firing battery to insure uninterrupted communication therewith. The proximity of good observation usually has a decided influence upon the selection of battery positions, especially where quick action is required in moving situations. Circumstances may sometimes demand observation through the gun sights to permit direct laying. 19. Concealment. — (a) Due to the ease with which an exposed battery may be neutralized by hostile fire, posi- tions for direct laying have become exceptional and are used only when absolutely necessary, or when there can be little or no danger of neutralization by hostile artillery fire. The sustained service of an artillery command can only be insured, in the face of an active enemy, by render- ing the guns inconspicuous or by entirely concealing them. Concealment from terrestrial observation is, as a rule, more important than concealment from aerial observation. A defilade of four yards from all hostile points of observa- tion is necessary to conceal the flashes of field guns (75- SELECTION OF POSITIONS 103 mm.) in daylight. To conceal the flashes of guns of larger caliber, this defilade must be considerably increased. If flash defilade is not possible, and a battery can be located by its flashes and by the conformation of the ground within very restricted limits, the battery is subject to neutralization or even destruction by hostile artillery fire. If, however, such a battery is located in a broad valley, and can be reached only by a searching fire with considerable depth, its chances of being able to sustain its fire are greatly increased. Gun Sight Line of Sight target—^ FIELD GUN WITH SIGHT DEFILADu Line of Vision ENEMY OP FIELD GUN WITH FLASH DEFILADE (b) Skill in the concealment of guns is acquired by careful study of the ground and by long experience on var- ied terrain. (1) From the enemy’s point of view positions on the sky line, or in front of a distinct background, usually are the most conspicuous. When the background is unfavorable to enemy observation, guns frequently are difficult to locate, even in the open. In the absence of natural cover, artificial means may be resorted to for concealing the guns. (2) A position in rear of a crest, especially when there are other crests about the same height in front or in rear, offers many advantages. Trees, hedges and standing grain may be utilized to mask hostile observation. (3) A position on a gentle slope, just far enough behind the crest to insure concealment of the flashes, best facilitates running the guns up to the crest should direct laying be called for. From the point of view of concealment alone, the most advantageous position is one more than 400 yards in rear of a covering mask, having flash defilade, and hidden from the view of any auxiliary observers that the enemy may push to the front or flanks. (4) Concealment from aerial observation is obtained by camouflage or by utilizing natural overhead cover to screen the guns, the ammunition and the approaches. (5) Concealment of approaches is important. If a battery can be seen by the enemy while approaching a position, efforts to locate the position occupied are greatly facilitated. VI— 20-21 104 TACTICS AND TECHNIQUE— ARTILLERY 20. Facility of Movement. — (a) When a position is selected for a battery, due consideration must be given to the feasibility of moving the battery quickly, in daylight or darkness, to some other position, and, in some cases, to the feasibility of moving the guns by hand to a direct fire position in an emergency. The latter consideration can apply only to light artillery. (b) A position to which guns are moved with difficulty, usually opposes even greater difficulties to their removal. Instances may be cited, also, in which guns were placed in position easily in good weather. A few hours’ rain, however, resulted in great difficulty and delay in moving them out. (c) An ideal battery position insures quick movement under cover to both front and rear, as well as to one or both flanks. 21. Favorable Conditions for Resupply of Ammu- nition. — (a) Covered approaches from the rear are es- sential to the resupply of ammunition in the daytime. Other- wise the flow of ammunition may be interrupted by hos- tile fire, or the battery position discovered by the movement of caissons or ammunition trucks bringing up ammuni- tion. (b) The first consideration in selecting positions for battalion combat trains, are protection from hostile fire, and covered approaches to the firing positions of the bat- teries. Other considerations are: ample space to permit parking the carriages with considerable intervals; ease of access to roads running back to the distributing point es- tablished by the ammunition train; facilities for visual or other communication with the battalion commander and the batteries. It is desirable that the distance to the firing batteries not exceed 1200 yards, but this distance may be somewhat increased when ample cover is not available. (c) When positions are occupied for long periods and when there are no prospects of a movement, both limber and combat trains may be established further to the rear, and, if possible, together, in order to facilitate administration and the supply of rations to both men and animals. When conditions permit such a procedure, ammunition may be VI— 21-23 SELECTION OF POSITIONS 105 supplied direct to the battery positions by the ammunition train, keeping the combat trains filled and ready for a re- sumption of movement. 22. Cover for Limbers or Gun Tractors. — The pre- servation of artillery mobility depends upon the protection of the teams or tractors from hostile fire. Maximum pro- tection, and free and prompt access to the guns, are the objects in view in reconnoitering positions for the limbers or tractors. The ideal position is one with vertical cover that affords protection against searching fire. When it is impracticable to conceal the limbers from the view of the enemy, they should be posted as far from the guns as the situation warrants, formed in line, faced toward the ene- my, with as wide intervals between carriages as the ground permits. 23. Gun Emplacements. — (a) Most heavy guns re- quire the installation of a special platform. Usually a field gun may be fired without any work on the gun emplace- ment; but if the soil is too hard for the trail spade to en- gage therein when the gun is fired, a narrow trench, about one foot deep, should be dug in the shape of an arc to provide a bearing surface for the trail spade. The length of the arc must be sufficient to permit laying the gun in any direction within its possible field of fire. If the soil is very soft, a similar trench should be dug, and the bearing sur- face for the trail spade (rear wall of the trench), revetted with fascines, logs or other material, preferably of an elas- tic nature. (b) An instance is known in The World War in which 155-mm. howitzers were fired in swampy ground. The trails did not bury themselves deeply, but the wheels were soon in the mud up to the hubs. Moving the gun carriages in azimuth became extremely difficult, and each time a how- itzer was fired, mud was splattered in all directions by the recoil of the breech into the mire. It was necessary to haul the howitzers from this position by means of block and tackle. (c) In selecting a battery position, sandy soil should be avoided. Dust is almost as bad. Sand and dust, blow- ing into the mechanism and adhering to the greased sur- VI— 23-24 106 TACTICS AND TECHNIQUE— ARTILLERY faces of the projectiles, are the causes of abnormal wear, and may result in putting guns out of action after a few rounds. (d) Flat horizontal ground or a gentle slope is de- sirable for a gun emplacement. If the ground slopes to one flank, the guns cannot be elevated in a vertical plane, with resulting errors in azimuth. With field guns, this condition may be corrected by digging a trench for the higher wheel, provided the slope is not too great. A steep slope to the rear will cause an abnormal recoil of a field gun carriage, resulting in considerable man-handling and consequent delay in moving the gun back up the slope. A forward slope greatly assists in checking the recoil of the gun carriages, but, to fire at long range, it may be necessary to dig deep holes for the trails in order to give the guns sufficient elevation. 24. Interference with the Operations of Other Troops. — (a) Sites selected for battery positions are us- ually far enough in rear of the front line to avoid inter- ference with the operations of other branches. The most desirable battery positions sometimes are found in close proximity to, or on the ground actually occupied by, com- mand posts, supports, reserves, or other troops or establish- ments. In such cases, the question that arises is not one of priority or preference as between one and another, but rather is a question of utilizing the avaliable ground in such manner as to secure the best possible teamwork under the circumstances. The decision rests with the commander of the whole. The criterion is, that the technical and tac- tical needs of any particular branch or element, as such, al- ways are subordinated to the good of the whole. (b) Due to the noise and the possibility of drawing hostile artillery fire, it is not pleasant to other troops to have a battery in close proximity. When unavoidable, this con- dition is tolerated without question. (c) Placing guns along the rear edge of a lateral road should be avoided, because of possible interference with traf- fic. It is well not to place batteries close to and on the leeward side of dusty roads, or too close to roads that are subject to heavy interdiction and harassing fire. VI — 24-26 SELECTION OF POSITIONS 107 (d) The batteries of a battalion or regiment usually are placed in position within the sectors assigned to the troops they support, but when, within an adjacent sector, better positions are available that do not interfere with the troops occupying that sector, arrangements usually can be made to occupy such positions. 25. Security of a Battery Position. — (a) Conceal- ment is a battery’s best security. Artillery should be free to devote its efforts to the support of the other arms and not be hampered by the necessity of protecting itself from attack. Battery positions usually are selected where they are amply protected by the proximity of other troops, but there are many incidents on record where the protecting troops have been driven back, and batteries sacrificed, the cannoneers engaging in a hand-to-hand conflict and serving the guns until the latter were disabled or captured. (b) In most of the battles of the Franco-Prussian War, German light batteries were hurried ahead, with lit- tle or no escort, to engage the enemy and cover the de- ployment of the infantry. The longer range of modern artillery makes this exposure unnecessary, and artillery escorts are now seldom required. (c) Artillery, in some unusual situations, is able to render battery support from positions to one flank rather than from positions directly in rear of the troops sup- ported. In such cases steps are taken to protect the guns from surprise or capture. 26. Protection of Guns and Personnel. — (a) As previously stated in this chapter, concealment is a bat- tery’s greatest protection. Elaborate battery emplacements can be built in the field only during periods of long stabiliza- tion, when concealment from continual aerial reconnaissance becomes almost impossible. The first step toward protec- tion is the digging of shallow emplacements for the guns, and of trenches for the protection of the cannoneers and ammunition. As time permits, the guns and ammunition are further protected by log or even concrete construc- tion, and the personnel by dugouts. VI— 26 108 TACTICS AND TECHNIQUE— ARTILLERY (b) From the above it can be seen that protection from hostile artillery fire is gained by the development of a battery position occupied for a protracted period, and is usually a very minor consideration in its original selection. VII— 1 CHAPTER VII Artillery Communications Paragraphs Section I. — General 1- 6 Section II. — Telephone 7-14 Section III. — Radio 15-18 Section IV.— Communication with Advancing Infantry. _ 19 Section V. — Pyrotechnics 20-21 Section VI. — Training 22 Section I General Paragraphs Means of Communication 1 General Characteristics 2 Dependence Upon Other Systems 3 Communication Between Artillery Units of the Same Command 4 Communication With Troops Supported by Artillery 5 Supervision and Coordination 6 1. Means of Communication. — (a) At present, ex- cept for communication with airplanes, main dependence for artillery communications is placed upon the telephone. The use of radio telegraphy by the artillery, in the past, has been confined almost exclusively to receiving messages from airplanes, in the adjustment of artillery fire by aerial observation ; but, in the future, with the rapid strides now being made in the development of radio telegraph and radio telephone equipment, radio communication will constitute an important auxiliary for communication between artil- lery units, and for communication between artillery and supported infantry. (b) No one means of communication can ever be con- sidered infallible, so that alternative means of communica- tion always must be immediately available, if not in actual operation. Advance in offensive operations is usually so rapid that the installation of telephone lines can seldom 109 110 TACTICS AND TECHNIQUE— ARTILLERY keep pace with the advance. Under such conditions aux- iliary means of communication must serve, at least tem- porarily, to the maximum advantage. (c) The various means of communication employed by artillery, for which equipment is issued, are: The telephone. The radio telegraph. The radio telephone. Visual signalling (semaphore and wigwag). Pyrotechnics. Motorcycle, mounted and dismounted messengers. (d) Buzzerphone and ordinary telegraph equipment is not at present issued to artillery units. The projector, though employed to a limited extent in The World War, no longer forms a part of the basic equipment for artillery units. However, it is believed that its use by artillery has not been discontinued permanently. (e) With the rapid advances being made in electrical devices for communication, equipment is constantly chang- ing, and it is impossible to look any distance into the fu- ture and say what the equipment will be. Practically all signal equipment in use by the artillery is issued by the Signal Corps, and it is mainly to the Signal Corps that the artillery looks for future development and improvement in this equipment. 2. General Characteristics. — Artillery in combat in- stalls, operates and maintains its own system of signal com- munications. The system of each battery, battalion, regi- ment and brigade is normally complete in itself and func- tions under the control of the commander of the unit, yet each system forms an integral part of the system of the next higher unit, and, for that reason, requires coordina- tion therewith. The communication system of any artil- lery unit must be coordinated and interlaced with the sys- tems of supported troops, or troops with which the ar- tillery unit is operating, including adjacent artillery units with which mutual fire support is arranged, 3. Dependence Upon Other Systems. — (a) If an ar- tillery unit depends upon exterior agencies for communica- tion vital to its own functioning in combat, in other words, if its system of communication is not complete in itself the VII— 3-4 GENERAL 111 efficiency of this unit in combat will depend largely upon the effective maintenance of a communication system over which it has no direct control. For instance, should a bat- tery depend upon a battalion axial telephone line for com- munication between the firing battery and an observation post from which fire is habitually conducted, the efficiency of this battery in combat will depend largely upon the main- tenance of this telephone line by the battalion. Even should it be effectively maintained, other needs for this battalion wire may interfere frequently with the conduct of fire of the battery. In the same way, a battalion should not be dependent upon a regimental line for communication with its batteries. Cases of this kind cannot be avoided always, but should be avoided whenever it is possible to do so. (b) On the other hand, in order to conserve both wire and labor, an artillery command must take advantage of systems of communication established and maintained by other units. These are used to provide for alternative means of communication between its various elements and with the troops supported, and to provide for communica- tion not so vital to its own functioning in combat, such as communication with other units of artillery, with flash and sound ranging stations, with observation squadrons, and with rear echelons of artillery headquarters and field trains. 4. Communication Between Artillery Units of the Same Command. — (a) Under the principle of independent communications outlined in the preceding paragraph, it appears that a battalion habitually establishes communica- tion with its batteries, a regiment with its battalions, and a brigade with its regiments. This is the system pre- scribed by our present regulations. (b) An economical compromise is made frequently by the use of an axial line. For instance, assuming a par- ticular case in which an artillery regimental command post is at a considerable distance in rear of the command posts of its battalions, the telephone personnel of the regimental headquarters lays an axial line forward and establishes a switchboard as a forward communication center at a point convenient to the battalion command posts. VII— 4 112 TACTICS AND TECHNIQUE— ARTILLERY (c) The diagrams below show an artillery regimental command post considerably in rear of the command posts of two of its battalions, but close to the command post of the third battalion (assuming a regiment of three battalions). In Figure 1, direct wire communication is established between the regimental command post and the command post of all of the battalions. This requires three miles of wire. In Figure 2 a regimental axial line is employed and the forward battalions are connected with the forward communication center. The amount of wire required is two miles instead of three. The employment of axial lines should not be carried too far. Direct communication usually is to be preferred, especially in the smaller units, for lines employed in the VII — 4-6 GENERAL 113 “conduct of fire” ; but axial lines frequently are desirable or necessary through considerations of time and economy. In Figure 1, by connecting the two forward battalion command posts, alternative and independent routes of tele- phone communication are established between the regimen- tal command post and both of these distant battalions. This is not possible with the system employed in Figure 2 . (d) Another important consideration to be taken into account in planning the system of communications for an artillery command is a more or less equitable distribution of installation, operation and maintenance, among the head- quarters of the various units of the command, in propor- tion to the signal personnel and equipment available in each. An illustration will be found in a later paragraph. 5. Communication With Troops Supported by Ar- tillery. — As an auxiliary arm, and largely dependent for its action in combat upon information from the troops sup- ported by its fire, artillery must bear the burden of estab- lishing and maintaining communication with the troops supported. In a moving situation there are few problems of communication more difficult than this, so that coopera- tion and assistance, upon the part of the troops supported frequently may be essential to the maintenance of this com- munication. 6. Supervision and Coordination. — (a) An artillery brigade commander, through his communications officers, has direct control over the communications established by the personnel of his headquarters, and supervisory control over the communications established by the subordinate units of his command. The same applies to regimental and battalion commanders. The communications within an ar- tillery command, vital to combat, are established usually as a matter of routine, but battery positions, observation posts and command posts are selected always with due regard to communications, not only communications within the ar- tillery command itself, but communications with other troops with which the artillery command is operating. It is there- fore obvious that, in any operation or in any movement, a plan of signal communications is an important considera- tion. In order that the system of each subordinate unit VII— (5 114 TACTICS AND TECHNIQUE— ARTILLERY may form an integral part of the system of the next higher unit, in order to make, where necessary, a more equitable distribution of installation, operation and maintenance, and in order to get the best results with the greatest economy of time, labor and materiel, there must be supervision, by higher units, over the communications established by sub- UU BtryC Bn. CP Q Bn C Tn CP of Supported Inf Beg I V Arty Reg'/\ Switchboard Figure 3 VII— 6 TELEPHONE 115 ordinate units, and there must be a spirit of harmonious cooperation among all the communicating officers of the command. (b) (1) As an illustration, consider a special case requiring su- pervision and cooperation in carrying out a plan of communica- tions. A battalion of light artillery takes up a position in a defensive situation. The sketch below is not intended to illus- trate either an ideal or a typical disposition, but serves to ex- emplify difficulties in communications that frequently may be expected. (2) The most essential battalion telephone lines, other than communication with the batteries, are shown in broken lines, re- quiring nearly two miles of wire. To connect the batteries with the battalion switchboards nearest thereto, requires an additional mile of wire. To establish telephone communication with the battalion combat train and with the command posts of two adja- cent artillery battalions (A and B) requires another two miles of wire. (3) There is but one reel cart with the headquarters of an artillery battalion. To establish and maintain five miles of tele- phone line is a great deal for a battalion headquarters to under- take. (4) In this particular case, the batteries have good observa- tion close at hand, on ridge 590 and on hill 625, and, consequently, have very short telephone lines to lay. Each battery has a reel cart of the same wire capacity as the reel cart of battalion headquarters. To save time, and to make a more equitable dis- tribution of the communications to be established and maintained, it is probable, in this case, that the battalion telephone officer would make the following recommendations to his battalion com- mander. (a) Battalion headquarters to establish and maintain only the lines shown in broken lines on the sketch. (b) Batteries to establish wire communication with the nearest battalion switchboard. (c) Battery B to establish communication with the ar- tillery battalion headquarters at B. In establishing field artillery communications, it is normal for lateral communi- cations to be run toward the left. So the battalion head- quarters at A should connect with the battalion on its left. (d) Battery C to establish communication with the bat- talion combat train. Section II Paragraphs Telephone Communications, Past and Present Telephone Equipment for Field Artillery Laying Telephone Wire Selection of Wire 7 8 9 lu VII— 7-9 116 TACTICS AND TECHNIQUE— ARTILLERY Battery Communications 11 Battalion Telephone Communications 12 Regimental Telephone Communications 13 Brigade Telephone Communications 14 7. Telephone Communications, Past and Present. — Before The World War, the switchboard was never used in our field artillery. The telephone system of an artillery command consisted of a number of independent lines, us- ually with ground return, and sometimes with several sta- tions on the same line. All stations on one line could com- municate with each other, but there was no means pro- vided for communication with stations on some other line. A compact instrument known as the service buzzer was employed on these lines. It combined both telephone and buzzer telegraph. This system was entirely supplanted during The World War by our present system, employing switchboards, field telephones and metallic return. 8. Telephone Equipment for Field Artillery. — The following items are extracted from the tables of basic allowances published in Circulars 178, 179, and 180, War Department, May 12, 1920: Article Btry Bn Hq Reg Hq Brig Telephones 6 6 6 12 Switchboards (different sizes) — 3 3 4 6 Breast reels with spools 4 4 2 0 Wire (for 75-mm.) kilometers Heavy twisted pair 5 10 15 Light twisted pair 8 5 2 Wir^ (for 155-mm. How), kilo. Heavy twisted pair 8 16 32 Light twisted pair 8 5 2 Wire (for brig Hq), kilometers Heavy twisted pair 50 9. Laying Telephone Wire. — (a) Spools for breast reels carry one-half mile of light twisted pair. Breast reels are carried by a single man either mounted or dismounted or may be rigged on a pack animal. Heavy twisted pair is issued on spools holding about one mile of wire. Four men can lay wire with one of these spools, two men carry- ing the spool on a crowbar or piece of pipe. This is a slow VII— 9 TELEPHONE 117 and tedious operation. It is a simple matter to rig up a spool on the back end of a truck. As a truck can carry several spools of wire it is well adapted to laying long lines of heavy twisted pair along good roads. Seven-strand twisted pair weighs 127 pounds per mile, eleven-strand 187 pounds per mile. (b) For all round use, especially on poor roads and across country, the reel cart provides the simplest means of laying heavy twisted pair. Reel carts can also pick up wire from the ground almost as rapidly as they can lay wire. Artillery reel carts hold about 3 miles of heavy twisted pair, but cannot carry a reserve supply. It re- quires considerable time to transfer wire from spools to the reel cart. One reel cart is furnished to each battery, battalion and regimental headquarters of light and medium artillery and one to the artillery brigade headquarters of an infantry division. They are drawn either by horses or tractors. (c) A hand reel 18 inches long and 10 inches in diam- eter is issued to batteries for attachment to a fifth section caisson. Light or heavy twisted pair may be used on this reel. It is very useful for running out short lines by hand from the firing battery. (d) Artillery telephone lines usually are laid along the ground, or suspended on existing poles, hedges or branches of trees. Traffic continually passing over wire at the same point will soon break the insulation, so that, where telephone lines cross roads or other traffic routes, they should be run through culverts, or suspended not less than 16 feet from the ground. (e) Wire laid on the ground should not be taut, but it will be so if the linemen are not careful to pull out plenty of slack while the wire is being unreeled. In order to pre- vent material displacement, wire laid on the ground should be secured to a tree, bush or other object every few hundred feet, particularly where there is a decided change of direc- tion. Wire laid loosely so that it “hugs” the ground is not liable to be broken by hostile artillery fire, except by a direct hit; neither is it so easily snapped when a horse gets his foot caught in it. VII — 9-11 118 TACTICS AND TECHNIQUE— ARTILLERY (f) When time permits, telephone lines should be tagged at frequent intervals with the designation of the organization to which the wire belongs. This is particu- larly necessary where many wires are run along the same route. 10. Selection of Wire. — An artillery command relies mainly upon heavy twisted pair for its telephone communi- cations. Light twisted pair is employed where it is danger- ous to expose telephone trucks and reel carts to enemy fire, and is especially valuable for keeping up observation of fire and communication with the infantry in an advance. A long line of light twisted pair is difficult to maintain, and will not give efficient service over more than a mile, when laid on the ground. Important lines of light twisted pair should be replaced by heavy twisted pair as soon as it is pos- sible to do so, 11. Battery Communications. — (a) In a battery of light artillery, a signal detail of 10 men (not including reel cart driver), and a reel cart drawn by two horses, are pro- vided for establishing, maintaining, and operating the bat- tery communications. The main reliance is the telephone, but semaphore or wigwag may be used for short distances. Fifteen combination flag kits form part of the equipment of a light battery. (b) The signal detail commences its operations as soon as the battery position, observation post and command post are selected. Communication is established usually before the firing battery reaches its position, firing data are cal- culated and transmitted, and hence the battery can open fire almost as soon as the trails of the guns are dropped. (c) The principal communications to be established are between the firing battery and the battery observation post or posts, and between the battery commander and the battalion commander. As discussed in a previous para- graph, the latter communication is established normally by the battalion headquarters. This communication us- ually is established by telephone, and is primarily a com- mand line between the battalion commander and the bat- tery commander. It may have other uses, including com- TELEPHONE 119 munication with the battalion radio station in the adjustment of fire by airplane observation. (d) This link between the battalion and battery tele- phone nets is established usually between the switchboard at the battery commander’s command post and the nearest switchboard of the battalion net. In a stabilized situation requiring a large amount of map firing and adjustments by aerial observation, the battery commander usually estab- lishes his command post at the firing battery, but in a mov- ing situation the battery commander generally conducts most of the fire by terrestrial observation from a battery observation post, and it is preferable, in such cases, to have the battalion wire run to that point. If the battery obser- vation post is not occupied after dark, the switchboard may be removed, and the line to the battalion commander con- nected to the line to the firing battery, thus giving direct communication from the battalion commander to the firing battery. (e) Communication with the position of the limbers is usually visual or by mounted messenger. The same ap- plies to communication with the combat train when the bat- tery is acting independently, and has extra caissons at- tached from the battalion combat train. (f) Unless acting independently as a tactical unit, a battery seldom has occasion to establish communication with other troops, unless required to do so in order to relieve the battalion signal personnel of part of its burden when a large number of battalion lines are to be established. (g) For medium artillery, the principles of battery communication are the same. The reel cart is drawn by a 5-ton tractor, and the signal personnel is transported on reconnaissance cars, motorcycle sidecars, and the reel cart. 12. Battalion Telephone Communications. — (a) A battalion telephone net may be compared to the local tele- phone system of a small town, except that the former may have more than one central station or switchboard. In the same way that the local telephone system of a small town is connected with the telephone systems of neighboring towns, the battalion telephone net is connected with the telephone nets of other units with which communication may VII— 12 120 TACTICS AND TECHNIQUE— ARTILLERY be necessary. The battalion communications officer in com- bat is responsible for the prompt development of a system of coordination with the communications officers of other units in order that efficient telephone service may be quickly es- tablished and maintained with all the units and headquarters with which the battalion has need for telephone communica- tion. (b) For the telephone communications of a light artil- lery battalion headquarters there are provided a reel cart with three drivers, a lieutenant as communications officer, two signal corporals, and 12 privates as follows : eight tele- phone operators, three lineguards, and a wireman on the reel cart; all mounted except the last named. Other per- Figure 4. Diagram of a battalion telephone communica- tions light artillery. Bn CO & Staff Bn Radio Sta Supported Infantry Unit Bn C Tn* LEGEND Switchboard Bn Arty Liaison Officer with front line infantry Artillery Regiment Batteries Artillery units with which mutual support is arranged. Observation Balloon One telephone for the operator at each switchboard Telephone □ O Lines laid by the battalion Line laid by either artillery regiment or battalion (normally by sii— — in regiment) _______ Lines laid by either battalion or batteries (normally by bat> talion ) — — Lines laid by either battalion or other units Line laid by balloon company Communication with Bn C Tn is not invariably established by telephone. VII— -12-13 TELEPHONE 121 sonnel of the headquarters battery may be called upon to supplement this detail, when necessary. The personnel and equipment for a 155-mm. howitzer battalion is approximately the same, except that the reel cart is drawn by a 5-ton tractor. The telephone personnel is transported on recon- naissance cars and motorcycle sidecars, as well as on the reel cart. 13. Regimental Telephone Communications. — (a) Regimental telephone communications correspond in prin- ciple to the battalion telephone communications discussed in the preceding paragraph. Usually a regimental head- quarters has fewer telephone communications to install than a battalion, and therefore should be prepared, when- ever necessary, to assist the battalions with their telephone installations. Frequently this may be accomplished by es- tablishing axial lines convenient for the battalions to use, especially in situations requiring a forward displacement of the battalions. The regimental communications officer, un- der the supervision of the brigade communications officer, is responsible for the supply and replacement of telephone equipment and wire to the batteries and to the battalion headquarters. As provided by tables of organization, the regimental communications officer is a captain and has a lieutenant as assistant. (b) For the signal communications of the headquarters of a light regiment, there are provided, exclusive of the ra- dio detail: two signal sergeants, two signal corporals, eight privates as telephone operators, five privates as line guards, all mounted, a reel cart with three drivers and a wireman on the reel cart. The telephone personnel for the head- quarters of a 155-mm. howitzer regiment is greater in number than that provided for the headquarters of a 155- mm. howitzer battalion, discussed in the preceding para- graph. VII — 13-14 122 TACTICS AND TECHNIQUE— ARTILLERY Figure 5.— DIAGRAM OF REGIMENTAL TELEPHONE COM- MUNICATIONS LIGHT ARTILLERY Arty Brigade Rear Echelon of Kegtl Hq Battalions Artillery units with which mutual support is arranged Observation Balloon LEGEND , — . Switchboard /-v _ . , Q Telephone — Lines laid by regiment x x x— Lines laid by brigade or regiment (normally by brigade) . Lines laid by regiment or battalions (normally by regiment) Lines laid by regiment or other units — Line laid by balloon company 14. Brigade Telephone Communications. — (a) Bri- gade telephone communications correspond in principle to the regimental and battalion communications already dis- cussed. Besides his responsibility for the telephone com- munications of brigade headquarters, the brigade commun- ications officer, under authority of the brigade comman- der, exercises general supervisory control over the tele- phone communications throughout the entire brigade. This supervisory control is for the purpose of insuring: (1) Efficient and hormonious installation, operation and maintenance of telephone communications throughout the brigade. (2) Equitable supply and replacement of telephone equip- ment and wire by the regimental communications officers. Figure 6- Brig CO and staff Radio Sta Message Center Brig OP when one i: established LEGEND VII— 14 TELEPHONE 123 (3) Uniformity in the system of instruction for telephone personnel. , _ (4) Effective interlacing of the artillery telephone system with the systems of other units. (5) Utilization, in the most efficacious manner, of existing telephone lines, or lines abandoned by the enemy. (6) Salvage of wire from discontinued lines. (b) The brigade communications officer must be closely associated in his work with the division signal officer. (c) For the artillery brigade headquarters telephone communications of an infantry division, there are provided : one telephone sergeant, one telephone corporal, six privates as telephone operators, and eleven privates as lineguards. All are mounted except six lineguards. A six-horse reel cart with three drivers also is provided. As provided by or- ganization tables, the brigade communications officer is a captain and has a lieutenant as assistant. (d) The telephone communications usually essential to brigade headquarters are shown diagrammatically as fol- lows: -Diagram of Brigade Headquarters Telephone Communications — Divisional Art. Corns Artillery Headquarters Division Hq Rear Echelon of Brig Hq and Am Tn Regiments Artillery units with which mutual support is arranged including the corps artillery brigade or subordinate units thereof One telephone for the operator at each switchboard Switchboard n X X *■ Telephones Lines laid usually by signal corps personnel Lines laid by brigade or regiments (normally by brigade) Lines laid by brigade or other units VII— 15 124 TACTICS AND TECHNIQUE— ARTILLERY Section III Radio Paragraphs Radio Communications Dependent Upon Available Equipment 15 Communication Between Airplanes and Artillery 16 Radio Communications Between Artillery Headquarters 17 Radio Communication with Infantry 18 15. Radio Communications Dependent Upon Avail- able Equipment. — (a) The present policy relative to radio telegraph and telephone equipment is toward development rather than toward immediate production. Circulars Nos. 178, 179, and 180, War Department, May 13, 1920, prescribe the basic allowances of radio equipment for field artillery units, yet the types prescribed do not exist in sufficient quantity to supply all units of our peace organizations. So rapid is the present development in military radio devices, that before the present authorized equipment could be man- ufactured in sufficient quantity to supply an army at war strength, this equipment would be superseded by more ad- vanced types. (b) In the event of war it would be necessary, at the beginning to make the best use possible of the radio equip- ment available and to expedite production of the most ad- vanced types that have been developed and that have been thoroughly tested under service conditions. (c) The practical employment of radio communications is largely dependent upon atmospheric conditions, includ- ing intentional or unintentional “jamming of the air.” It is now the most important means of communications be- tween airplanes and ground troops, but no matter how highly developed, can never supersede in importance the field telephone for communication between stations on the ground. Nevertheless, there will be instances in which the radio would be of greater utility to the artillery than the field telephone, and perhaps many instances in which it will be the only practical means of communication in a crisis. VII— 16 RADIO 125 16. Communication Between Airplanes and Artil- lery. — (a) The occasions for this communication are as follows: (1) With batteries, through battalion headquar- ters, for the adjustment of fire by airplane observation; (2) with battalion or other headquarters, to inform artillery units of the location of suitable targets discovered by an airplane observer, or other information of value to the artil- lery. (b) The present method of communication, in the ad- justment of artillery fire is by two-way radio telephone com- munication between airplane and radio station at battalion headquarters, and wire telephone communication between the radio station and the battery. There is under develop- ment at this time a switching device to be used in connec- tion with the radio telephone, by means of which communi- cation with the airplane can be carried on directly with the firing battery. With this device, the radio signals from the airplane are received at the battalion radio station, and transmitted over the ordinary field telephone to the bat- tery. The battery replies over the ordinary telephone to the battalion radio station where the special switching de- vice transfers the message to the radio telephone, by which it is sent directly to the airplane. (c) Should radio telephone communication fail, the radio telegraph is resorted to, and the following would be the usual cycle of communications during the adjustment of fire: Airplane to battalion radio station by radio telegraph mes- sage, employing a code of abbreviations. Battalion radio station to firing battery and return, by wire telephone. Battalion radio station to airplane by panel signal. (The panel signals employed for this communication are given in the appendix of “Signal Communications for All Arms, G.S.S., 1922.”) (d) In special cases, airplanes may communicate with artillery units by means of dropped messages, or by a pre- arranged code of pyrotechnic signals. The latter is of espe- cial value in controlling the rate of advance of accompany- ing fire during an attack, when other means of keeping track of the infantry rate of advance fail. VII— 16-17 126 TACTICS AND TECHNIQUE— ARTILLERY (e) All radio stations at artillery command posts are equipped with identification panels differing in design. (See Appendix to Signal Communications for all Arms, G.S.S. 1922). They must be conspicuously displayed in order to be seen from an airplane at a high altitude. Where many radio stations are grouped within a restricted area, it is difficult for the airplane observer to pick out the panel of a particular unit unless its location is known beforehand. It is therefore essential that the air service unit working with an artillery command be notified promptly of any change in the location of panels. 17. Radio Communications Between Artillery Headquarters. — (a) In The World War, the use of the radio telegraph by the artillery was confined almost exclu- sively to receiving messages from airplanes and meteorolo- gical stations, and intercepting messages that might con- tain information of value. Two-way radio telegraph com- munication was provided between the headquarters of an artillery brigade and the headquarters of its regiments, but this communication was seldom used. The headquarters of the division artillery brigades were equipped with radio telegraph for communication with division headquarters and with the headquarters of infantry brigades. The utility of this station in the division net is questionable. (b) The present program of development contemplates eventual radio communication for division artillery as fol- lows: (1) Artillery brigade net: Brigade headquarters. Headquarters of 75-mm. regiments. Headquarters of attached 155-mm. regiments. (2) Artillery regimental net: Radio telegraph employing the S. (75-mm. regiments.) C. R. 77-A loop set (see also Regimental headquarters. par. 18). The headquarters Headquarters of battalions. of battalions are provided with the S. C. R. 109 set, primarily for intercommunication by ra- dio telephone with observing planes. This set may be used for radio communication with regimental headquarters in an emergency. Radio telephone and telegraph em- ploying the S. C. R. 109 set. (Used also for radio telephone communication with observing planes.) VII— 17-18 RADIO 127 (c) Normally the headquarters of a division artillery brigade is included in the division net, with radio telegraph communication with division headquarters and the head- quarters of infantry brigades, employing the S.C.R. 79-A set for this purpose. The corps plan of signal communica- tions may authorize the employment of this set for radio telegraphic communication with corps and army artillery. (d) In the cavalry division, it is contemplated equip- ping every battalion and battery headquarters of horse ar- tillery with the S. C. R. 109 radio set. In the pack artillery, it is contemplated equipping only the battalion headquar- ters with the same set, arranged for pack transportation. 18. Radio Communication With Infantry. — The in- novation of a light weight radio telegraph set that can be carried easily by two or three men, that can be set up quick- ly for transmitting and receiving, and that is provided with a break-in feature by means of which a message may be in- terrupted for any necessary repetition, opens up new pos- sibilities for solving that most difficult problem — communi- cation between advancing infantry and its supporting ar- tillery, This radio telegraph set, the S. C. R. 77-A, will be utilized in the future for inter-communication between the following headquarters : Headquarters of: 1 Light artillery regiment, 2 Light artillery battalions, 2 infantry regiments, 4 infantry battalions (assuming that each infantry regi- ment has 2 battalions in line, and one battalion in re- reserve, the latter not requiring radio telegraph com- munication). As the S. C. R. 77-A set has nine different and non-in- terfering wave lengths, a different wave length will be as- signed to each of the nine stations in this net, and a maxi- mum of four messages can be transmitted at the same time between four pairs of stations within this net. VII— 19 128 TACTICS AND TECHNIQUE— ARTILLERY Section IV Communication with Advancing Infantry Paragraph Communication with Advancing Infantry 19 19. Communication with Advancing Infantry. — (a) In a defensive situation, or in a withdrawal, the mainten- ance of communications with supported infantry does not present a problem that compares in difficulties with the maintenance of communication when the infantry is mov- ing forward. The latter is the most difficult problem of communications with which the artillery must cope. (b) A few accompanying batteries, or accompanying guns, by frequent changes of position, may keep pace with the infantry advance and maintain close connection there- with, but the bulk of the supporting artillery of large com- mands usually must fire during a day’s operations without more than one or two changes of position. Under these con- ditions, to obtain the greatest efficiency from artillery ac- companying fire, two important problems in forward com- munications present themselves: First. — Battery commanders must continue to provide for the technical observation of their accompanying fire, in order to make it fit the needs of the infantry. Second. — Artillery battalion commanders must maintain tac- tical connection with the commander of the infantry assault bat- talions. Though closely related, both of these problems require independent communications. (c) The accompanying fire of a battery sometimes may be observed from an exceptionally good observation post up to the extreme limit of range of the guns; balloon and air- plane observation may be of great assistance; but usually a battery commander must provide for moving his terres- trial observation forward to successive points of vantage, keeping pace with the infantry advance. The first obser- vation post must not be abandoned until communication has been established with the second and it is ready to function ; and so on. In close country, where observation for any con- siderable distance is impossible, battery observation details VII— 19 COMMUNICATION WITH ADVANCING INFANTRY 129 must accompany the infantry assault battalions, and be pro- vided with the necessary means of communication with their batteries. Communication with the batteries should be by telephone whenever possible, with all available auxil- iary means held ready should telephone communications fail. (d) Considering now the second problem : tactical con- nection with infantry assault battalions is insured by means of an artillery battalion liaison officer with the commander of each assault battalion. Each liaison officer must be pro- vided with sufficient personnel and equipment to maintain communication with the commander of the supporting ar- tillery battalion to which he belongs. Also he must be pre- pared to conduct the fire of a battery in cases where artil- lery fire must be adjusted on a particular target visible to him, but for which no battery observation is available. For this communication between artillery liaison officers and ar- tillery battalion commanders the telephone usually is to be preferred, but no means of communication is infallible and for that reason no one means of communication should be depended upon to the exclusion of others. Though every effort should be made to maintain telephone communica- tions, provision should be made to have these important communications function with the idea that the telephone lines will be out. Runners should be available, also motor- cycle or mounted couriers if conditions warrant, and projec- tors may be utilized for one-way communication (front to rear) . (e) A loop radio telegraph set is provided to infantry battalion commanders to supplement the communications maintained by the artillery personnel, and in time it is not unlikely that artillery battalion liaison officers will be pro- vided with radio equipment for the establishment of this radio communication. VII— 20-21 130 TACTICS AND TECHNIQUE— ARTILLERY Section V Pyrotechnics Paragraphs Pyrotechnics in an Advance 20 Pyrotechnics in Defense 21 20. Pyrotechnics in an Advance. — (a) Any use made of pyrotechnics for the transmission pf messages from assaulting infantry to supporting artillery must be carefully prearranged. (b) Under conditions of good visibility, a message can be conveyed instantaneously to several units, that might re- quire several minutes to relay by telephone. (c) The required prearrangements for the use of pyro- technics are : (1) A definite understanding as to the meaning of each signal or combination thereof. (2) A prearrangement of points or rocket posts from which pyrotechnics signals intended for any particular artillery unit or units are to be fired. This is necessary in order to avoid con- fusion with enemy pyrotechnics. For each pyrotechnic detail, successive points or rocket posts must be decided upon, so that the detail may proceed from one to another, keeping pace with the infantry advance. As each successive rocket post is abandoned a prearranged signal may be fired to indicate this fact. (d) The signals prearranged should be as few in num- ber as possible. Only the simplest and most reliable pyro- technics should be employed. It is dangerous to assign dif- ferent meanings to one-star, three-star, and five-star rockets of the same color, for the reason that some of the stars might be obscured by the rocket bursting low. 21. Pyrotechnics in Defense. — (a) In defensive situations, the infantry units, occupying centers of resis- tance that are in danger of attack by the enemy, usually , are provided with pyrotechnics for the purpose of calling upon the supporting artillery for defensive fire in the form of counter preparations and barrages. The signals are fired usually by infantry personnel. They are fired invari- ably at rocket posts agreed upon with the supporting artil- lery. VII— 21-22 TRAINING 131 (b) Rocket posts are first established in the immediate vicinity of the outposts. In case an outpost may be with- drawn if attacked, rocket posts should be provided for in the immediate vicinity of the line of resistance next in rear thereof. (c) A rocket post must be established so that good com- munications are insured to all parts of the defensive posi- tion that the defensive fire, called for from this rocket post, is intended to cover. It must also be established in such a position that its signals can be clearly seen by the support- ing artillery units. (d) The batteries must have observers continually watching the rocket posts from which signals are fired to which they must respond with defensive fire. These obser- vers must be provided with means of knowing the exact directions to the rocket posts they are required to keep un- der observation. Otherwise there may be confusion with pyrotechnics fired from other rocket posts or with enemy pyrotechnics. An improvised rocket board, or stakes set in the directions of the rocket posts, will answer the pur- pose. Section VI Training Paragraph Training of Artillery Signal Personnel 22 22. Training of Artillery Signal Personnel. — (a) There is some difference of opinion, among field artillery officers, as to how personnel for artillery communications should be obtained. All artillery communications are for one purpose ; the efficient tactical and technical employment of the guns . The first training of signal personnel and all other specialists should be with the gun squads of the firing battery. Communications specialists who have had this training, gain a spirit of cooperation with the firing units that cannot be inculcated in any other way. Specialists VII— 22 132 TACTICS AND TECHNIQUE— ARTILLERY who have not had this training, almost invariably look upon the service of the guns as an auxiliary to their own work. (b) Training must be standardized. Methods in one unit should not differ from those in another. Understudies should be in constant training and ready to take the place of any specialists. In the use of Signal Corps equipment, Signal Corps methods must be carefully adhered to. VIII— 1-2 CHAPTER VIII General Principles Governing the Tactical Employment of Artillery Paragraphs Basis of Tactical Use 1 Characteristics 2 Limitations 3 Effect of Limitations 4 Purpose of Field Artillery 5 The Infantry-Artillery Team 6 Artillery Tactics Defined 7 No Independent Artillery Role 8 Utility of Study 9 Information the Artilleryman Must Have 10 Battle Units 11 Primary Mission — Division Artillery 12 Organization for Combat 13 Disposition of Attached Artillery 14 Disposition for Command 15 Decisions Concerning Artillery Employment 16 The Division Order 17 1. Basis of Tactical Use. — The general principles governing the tactical employment of field artillery are based upon the characteristics and limitations of this branch. 2. Characteristics. — (a) The basic characteristics of field artillery are : (1) Great fire power concentrated in a relatively small tac- tical unit. (2) Rapidity of fire. (3) Long range. (4) Ability to act from concealed positions. (b) The first characteristic, great fire power concen- trated in a relatively small unit, facilitates intelligent direc- tion. It enables a commander to hold a powerful force well in hand and to bring it to bear with the desired intensity at the proper place and time. (c) The second characteristic, rapidity of fire, enables artillery to bring a crushing fire to bear upon a vulnerable enemy before he can escape from its action. (d) The third characteristic, long range, permits great freedom of action, by enabling it to interpose its fire effec- 133 VIII- — 2-6 134 TACTICS AND TECHNIQUE— ARTILLERY tively over a broad terrain and to secure the concentration of effort of widely dispersed units. (e) The fourth characteristic, ability to act from con- cealed positions, facilitates establishing the guns in favora- ble positions, facilitates surprise action, preserves freedom of maneuver, and makes it possible for inferior artillery to remain on the battlefield. 3. Limitations.— A rtillery, on the other hand, has certain limitations which prevent its employment as an inde- pendent, self-sustaining branch. Among these are : (a) Artillery is unable to act otherwise than by fire action. As it must fire from position, and as its changes of position must be few, it is not, like infantry and cavalry, capable of continuous maneuver in battle. (b) Artillery is extremely vulnerable when exposed, in the open, to percussion fire at medium ranges ; and when exposed to shrapnel fire in route formation, or when chang- ing position, as it can protect itself only with difficulty by fire action, or by concealment or escape. Even when unlim- bered, it is difficult to defend itself against attacks on its flanks and rear. 4. Effect of Limitations. — These limitations prevent the employment of the artillery as an independent, self- sustaining branch. It is always an auxiliary branch — by itself, it can do nothing. 5. Purpose of Field Artillery. — “The reason for the existence of the field artillery is its ability to assist the other arms, especially the infantry, upon the field of battle. The degree to which field artillery prepares itself to render this assistance is then the measure of its training.” ' This quota- tion constitutes the first paragraph of the Field Artillery Drill Regulations, which shows the importance attached to it by the artillery. It is the first principle taught the field artilleryman as the purpose of his training. 6. The Infantry-Artillery Team. — Success in com- bat, in all but very minor operations, is dependent, primar- ily, upon the mutual support of the infantry and artillery. Artillery prepares the way and assists the infantry, but it cannot alone carry an attack to a definite conclusion. Infan- try, on the other hand, requires the support of the artillery VIII— 6-9 GENERAL PRINCIPLES— TACTICS 135 in order to make the advance with minimum loss ; therefore, both work together as mutually interdependent parts of the combined arms. 7. Artillery Tactics Defined. — (a) Artillery tactics is defined as the art of disposing artillery troops, guns, am- munition and communications in the presence of the enemy so as to apply its maximum fire power in such a manner as will assist the infantry in accomplishing its mission. (b) The definition given goes into more detail than usual in enumerating the different elements of the artillery command. The words artillery, or artillery troops, usually have been accepted as sufficiently comprehensive, but it is desired to emphasize the importance of all the primary ele- ments of the artillery team (troops, guns, ammunition and communications) and the internal as well as the external cooperation necessary in the efficient handling of this arm. 8. No Independent Artillery Role. — The exact method of employing field artillery depends, as in the case of the other branches, upon the particular tactical situa- tion; but, in addition, its use always must conform to the plan decided upon by the commander of the troops which it supports and under whose orders it acts. For this reason, an artillery commander, unlike the commanders of the other primary branches, has no independent role as a tactician ex- cept in so locating the units of his command as best to ren- der the assistance required by the troops which his com- mand supports. 9. Utility of Study. — An infantry or independent cavalry force is usually commanded by an infantry or cav- alry officer. Artillery, as an auxiliary to such a force, is al- most invariably under the command of an officer of another arm. Therefore, for the good of the service at large, it is important that officers of other arms study its characteris- tics. The commander of a mixed force containing artillery often finds himself in difficulties when it comes to the utiliza- tion of his artillery. He is liable to make one of two mis- takes ; he will either so hamper his artillery with unwise and impossible orders that its energy is wasted ; or he will leave his artillery commander to his own devices, without even giving him information that would enable him to act intel- VIII— 9-11 136 TACTICS AND TECHNIQUE— ARTILLERY ligently. He should not deprive himself of the expert ad- vice of his artillery commander, but he should be able to pass judgment upon the suggestions offered. Then, when he gives an order to his artillery, he can give it with confidence, on his own responsibility — not merely approve, as a matter of routine, the recommendations made by his adviser. 10. Information the Artilleryman Must Have. — (a) When fire is ordered or requested on a certain target, the artilleryman must be given sufficient information to enable him to act intelligently. The following information is essential: (1) Target must be accurately designated, and if possible the nature of the target described. (2) The object of the fire must be stated, in order that the proper ammunition and fuse may be selected and the number of rounds required to accomplish the object in view calculated. (3) The time limit is of great importance when our infan- try is advancing toward the target. (b) Instances in The World War are known in which our advancing infantry sent messages to the artillery re- questing fire on a particular woods. The artilleryman re- ceiving this message did not know what time the message was sent, nor how long it took the message to reach him. He did not know how long the infantry would wait for this fire before attempting to advance. He had to guess at the ob- ject of this fire and at the part of the woods upon which to direct his fire. It is always the best policy to transmit messages calling for artillery fire through the artillery liai- son officers with front line units, in order to insure these messages containing all the information required. 11. Battle Units. — (a) There has been much diver- sity of opinion as to when and to what extent an artillery command should be broken up, and all of it, or parts of it, attached to temporary battle units. The division is the smallest unit to which artillery is organically assigned, yet circumstances sometimes require that a brigade, a regiment, or even a battalion have artillery temporarily attached to it, and placed directly under the orders of the commander thereof. The decision must be made by the division com- mander. If he thinks that his subordinate can carry out his task only by having full control of all his troops, the division commander should give him the necessary amount VIII— 11-12 GENERAL PRINCIPLES— TACTICS 137 of artillery unconditionally, and take the chance of not be- ing able to get hold of it again promptly. It would be very unusual to attach all the division artillery to subordinate infantry units, unless the action develop into a number of local and almost independent engagements over which the division commander has, temporarily, little or no control. Powerful concentrations of artillery fire at particular points are frequently essential to the success of the division as a whole, so that the division commander, through his artillery brigade commander, must have control, ordinarily, over a sufficient amount of artillery to execute these concentra- tions quickly and effectively. This requires good communi- cations and cannot be accomplished with too great a dis- persion of the division artillery. The execution of artillery fire in support of the division as a whole may be made the primary mission of some units of the division artillery. To other units this may be assigned as a secondary mission, with a primary mission of supporting a particular infantry unit without being actually attached thereto. (1) The infantry division is the combat unit of the combined arms. Within this combat unit all branches are knitted together into a fighting team. The basis of organization of this fighting team is its infantry units. The fighting team is organized into infantry groups and supporting fire units. (2) Each infantry group generally comprises, or has closely associated with it, elements of all branches of the division. The infantry commanders are the leaders of these groups and coordinate the fighting powers of all the branches included in their respective groups. (3) The supporting fire units comprise units of artillery. They are employed by the division commander to support, by fire, any or all of the infantry groups indicated above and to assist infantry groups of adjacent divisions. (4) Bearing in mind the composition and functions of the infantry groups and supporting fire groups indicated above, several different combinations are available to meet special situa- tions. As an example, all artillery may be retained in the sup- porting fire units while, at the same time, specific elements of these fire units are closely associated with specific infantry groups. (b) The principles indicated above form the basis of the role and command of division artillery in action. 12. Primary Mission — Division Artillery. — The pri- mary mission of the division artillery is to support the in- fantry of its own division by firing on those hostile elements which are causing losses to the infantry, impeding its ad- VIII — 12-13 138 TACTICS AND TECHNIQUE— ARTILLERY vance, or imperiling its security. The division artillery, therefore, has, in general, no independent battle role or mis- sion. (See Artillery Drill and Service Regulations, para- graph 1466.) The main purpose of the division artillery in battle should be to cooperate with the infantry by meeting the needs of the latter in fire power. All instructions, or- ders and the conduct of the division artillery should be based on, point to and seek the closest cooperation with the infan- try it supports. 13. Organization for Combat. — (a) For practical operation in rendering the assistance indicated above, aside from questions of command, it is possible to organize the division artillery in three ways: (1) First, to apportion all the division artillery to support of the subdivisions of the infantry, “infantry groups” mentioned in a previous paragraph. Each artillery subdivision is then given the primary mission of supporting closely a particular infantry unit, and a secondary mission of firing in support of other infantry units or the division as a whole. The foregoing method makes for close cooperation between infantry and artil- lery by establishing teamwork between specific infantry and ar- tillery units. At the same time, it permits all of the supporting artillery that is not fully committed to its primary missions, to take part in concentrations of artillery fire on localities desired by the division commander. (2) Second, to maintain continuously the division artillery as a separate and distinct tactical unit of the division, which places its fire on appropriate points with respect to the infantry as a whole. (3) Third, a combination of the foregoing methods, appor- tioning part of the division artillery to support infantry subdi- visions, and retaining the remainder for the support of the divi- sion as a whole. The primary and secondary missions of the ar- tillery units that are apportioned to support infantry subdivisions, remain the same as outlined in the first method above. The mis- sion of that part of the division artillery apportioned to support the division as a whole, is to participate in such fires as may be desired by the division commander. (4) NOTE. — Habitually, one regiment of light guns must train with one of the infantry brigades to the point that it ac- tually feels itself to be a part of the brigade. In the artillery regiment, the same battalion should, whenever possible, serve the same infantry regiment. Throughout his entire team, the divi- sion commander and his staff must force this intimate daily con- tact and cooperation, requiring at the same time the senior ar- tillery commander to coordinate all the artillery fire so as to insure the success of the team. (Superior Board, A. E. F.) (b) The first method will be used habitually ; the second method is not applicable in any tactical situation, as the first and third methods make suitable and ample provisions for VIII — 13-15 GENERAL PRINCIPLES— TACTICS 139 emergency and rapid concentrations of fire. The use of the third method will be very exceptional except in the case of medium and heavy guns or howitzers attached to the divi- sion artillery. (c) The amount of artillery retained to support speci- fic infantry units, and the amount retained to support the division as a whole, are questions for the division comman- der to decide in each situation. Generally, all of the light artillery supports specific infantry units; some or all of at- tached 155-mm. howitzers may be so assigned or all may support the division as a whole. When the division artillery is heavily reinforced, some of the reinforcing light artillery may support the division as a whole. (d) By designating, whenever practicable, the same artillery regiment to support a specific infantry brigade, or the same artillery battalion to support a specific infantry regiment, teamwork and mutual cooperation between in- fantry and artillery are developed. 14. Disposition of Attached Artillery. — (a) Me- dium howitzers, usually a regiment, may be attached to the division from the corps artillery, when the division is acting alone, or when there are special reasons for such attach- ment. When attached to the division, medium howitzers form part of the division artillery, and normally support the division as a whole. When circumstances make it advisable, a battalion of medium howitzers may be associated with a light artillery regiment, with a secondary mission of answer- ing special calls to supplement the fire of the light guns in support of infantry subdivisions. (b) When the division artillery is reenforced by other battalions, regiments or brigades of light artillery, the dis- positions and missions thereof are questions for the divi- sion commander to decide. 15. Disposition for Command. — (a) From the view- point of command, there are two recognized dispositions of the division artillery: (1) That retained under the artillery brigade commander, termed supporting artillery. (2) That attached to subordinate infantry or cavalry units. This includes artillery with advance ,rear, or flank guards, or with a small detached force, such as a reinforced brigade. Also accompanying batteries and accompanying guns, when used. VIII— 15-16 140 TACTICS AND TECHNIQUE— ARTILLERY (b) (1) In principle, some of the division artillery is attached to infantry units whenever the action has resolved, or is likely to resolve, itself into disconnected local engagements. In such cases, local infantry commanders require artillery support con- trolled by themselves, as they, and not superior commanders, are conversant with the local situations and are responsible for de- cisions and actions thereon. (2) It should be borne in mind, however, that artillery thus attached is not readily available for division concentrations; the number of guns therefore should be relatively small, and their use confined to situations where supporting artillery is not equal- ly effective. (c) In defensives, and at least in the initial stages of offensives, in open warfare situations, the division artillery is in principle used to support, and no detachments there- from are made. In pursuits, retreats, meeting engagements, and security functions, and other such situations in which the division cannot be employed as a coordinated whole, some attached artillery is the rule ; in exceptional cases, all of the division artillery may be so disposed. (d) Artillery ordered to support a specific infantry unit has the role of closely supporting that unit with its own fire, and of securing additional fire from other support- ing units, when its own is inadequate or not suitable in type for a particular mission. It has the additional role of delivering other fires directed by the division commander. (e) In order that the collective missions ordered by the division commander may be carried out to best advan- tage, the division artillery commander formulates plans to meet possible needs in this connection. These plans vary in extent, depending on the time available and the situa- tion. (f) However, in any situation, the division artillery commander is given such tactical control of all the support- ing artillery that the orders of the division commander for collective missions may be carried out promptly and effec- tively. 16 . Decisions Concerning Artillery Employment. (a) While the selection of the exact position to be occupied by batteries, etc., is a function of the junior artillery com- manders, the division commander selects the general local- ity for each artillery regiment. In making this selection, the division commander considers not only the infantry unit VIII— 16-17 GENERAL PRINCIPLES— TACTICS 141 the artillery regiment supports, but also the questions of road circulation, traffic control, supply and evacuation. In order to secure smooth working of the whole divisional team as well as close cooperation between the infantry and the supporting artillery, the division order should announce, in all offensives and defensives, the general localities se- lected. (b) The command of the artillery brigade of an infan- try division is exercised in the same manner as that of an infantry brigade. It should be thoroughly understood that in arriving at decisions governing the dispositions and em- ployment of the division artillery, the artillery brigade com- mander is the chief adviser of the division commander. Nevertheless the actual decisions, in the cases cited, are functions of the division commander and not of the artil- lery brigade commander. 17. The Division Order. — (a) In attacks and de- fenses, the division commander's order should cover : (1) The artillery unit or units to support each large infan- try unit. Whenever possible, the same artillery habitually sup- ports the same infantry unit. In a stabilized defensive sector, where frequent changes are made in the infantry units occupying the position, the artillery may be ordered to support a defined ter- rain area (sector). (2) The general locality in which each artillery regiment is to be placed. (3) Any attachment of artillery units to infantry commands. (4) Any special targets or missions, and any special direc- tions as to gas and smoke. (5) General directions as to forward movement or retire- ment of the artillery if any is contemplated. (b) In framing the division field order, the subpara- graph of paragraph 3, relating to the artillery, is drafted in consultation with the artillery brigade commander. His recommendations thus are given consideration, and he se- cures early information to enable him to prepare the artil- lery brigade field order. IX— 1 CHAPTER IX The Tactical and Technical Employment of the Battery Paragraphs The Battery a Technical Unit 1 Light Battery the Standard 2 Composition and Subdivision 3 The Battery Headquarters 4 The Battery Detail 5 Battery Reconnaissance (See also Chapter VI) 6 Orders of the Battery Commander 7 The Firing Battery 8 Battery Combat Train 9 Ammunition • 10 Batteries Employed Independently (See also Chapter XIII) __ 11 Change of Position 12 Communications 13 Administration and Supply 14 Conduct of Fire 15 Observation of Fire 16 Map Firing 17 1. The Battery a Technical Unit. — The battery is a technical unit. Its fire power is directed and controlled by one man. Its effectiveness in combat is largely depen- dent upon technical efficiency. To give a battery comman- der the additional burden of tactical responsibilities, tends to detract from the battery’s technical efficiency and to impose upon the personnel of the battery headquarters ad- ditional duties for which it is not organized nor adequately equipped. For this reason, the tactical handling of batteries associated with, or supporting troops of other arms, is cen- tered in the battalion commander. A battalion commander should concern himself as little as possible with the techni- cal details of fire accuracy, and should remain free to direct his energy and attention toward the tactical employment of the fire power of his batteries so as best to carry out the plan of action of the commander of the troops he is support- ing. The duties of the battalion commander and his head- quarters, in this connection, are discussed in the next chap- ter. 142 IX— 2-4 TACTICAL— TECHNICAL EMPLOYMENT— BATTERY 143 2. Light Battery the Standard. — (a) For field ar- tillery employment, the light battery, horse-drawn, is the standard. In designing the light field gun, sufficient power has been sacrificed to give it the mobility to keep up with infantry under normal conditions. Other types of artil- lery are substituted for particular employment. Where greater mobility is required, horse artillery or portee artil- lery is substituted. In mountainous country, or where the terrain is impracticable for horse or tractor-drawn trans- portation, light artillery is replaced by pack artillery. When movement is slow, or greater power is required, guns and howitzers of larger caliber are brought forward. Each class of artillery has its particular uses, and it is not a matter of indifference whether heavy howitzers or light guns are assigned to a particular task, any more than whether a par- ticular mission should be assigned to cavalry or to infantry. (b) In the paragraphs that follow, the discussion is based upon the employment of light artillery, but, unless specifically excepted, the principles are applicable to the heavier types of artillery that accompany troops in the field. 3. Composition and Subdivision. — In our army, all light, medium or heavy artillery batteries that accompany troops in the field are equipped and manned for the service of four guns or howitzers. The personnel and equipment provided to a battery for communications, computation of firing data and observation of fire, are adequate normally for only one firing unit. Consequently, the utilization of detached platoons or of single guns should be avoided when possible. Especially is this true in the case of the 75-mm. battery. The principal subdivisions of a battery are: 1. The battery headquarters. 2. The firing battery. 3. The maintenance section. Each will be considered in some detail. 4. The Battery Headquarters. — The headquarters of a 75-mm. battery (horse-drawn) consists of 2 officers (1 captain as battery commander and 1 second lieutenant as reconnaissance officer), 26 enlisted men, a 4-horse reel cart, and a 4-horse f-ton spring wagon for carrying instruments and additional wire. IX— 4 144 TACTICS AND TECHNIQUE— ARTILLERY The principal functions of the battery headquarters are briefly as follows : Functions Command and administration. Reconnaissance and security (also liaison with supported infantry when battery is acting alone). Establishment and maintenance of observation. Conduct of fire, calculation of firing data, and any topogra- phical work connected there- with. Establishment and maintenance of battery communicatins. Liaison with artillery battalion commander. Liaison with the limbers, when the battery is in firing posi- tion, and with the firing bat- tery when the headquarters is separated therefrom on the march or during a re- connaissance. Marking the route for the firing battery. By Whom Performed Battery commander assisted by 1st sergeant and battery clerk. Battery commander assisted by re- connaissance officer and two scout corporals. Battery* commander assisted by re- connaissance officer, instrument sergeant and four instrument men. Same. Signal sergeant, two signal cor- porals, five telephone opera- tors, two line guards, and reel cart with drivers. Battery agent.* 1st Sergeant. Under the direction of the 1st Ser- geant.f *Designated as “battalion agent” in Table 38W, Tables of Or- ganization, 1921. fWhen the battery commander with his detail goes forward on reconnaissance, he is followed by his battery at a slower gait. Upon reaching any point where the officer with the battery might be in doubt as to the proper direction to take, the first sergeat drops off a man, as a “marker.” The first marker waits for the approach of the battery, and as soon as he has indicated to the officer at the head of the battery the direction to be followed (usually by a signal acknow- ledged by the officer), he rides forward at an increased gait until he comes to the second marker. He relieves the second marker who in turn rides forward to relieve the third. This process is continued. When the battery commander arrives at a point where he wishes the battery to halt until the completion of the reconnaissance he calls out “Last Marker.” IX— 4-5 TACTICAL— TECHNICAL EMPLOYMENT— BATTERY 145 In addition to the administrative and technical person- nel of the battery headquarters, a bugler and three horse- holders are provided. 5. The Battery Detail. — (a) Eliminating from the battery headquarters the battery commander, the battery agent (usually with the battalion commander), the battery clerk (usually with the rear echelon of the regiment), and one telephone operator with the firing battery, we have what long custom in our service has been pleased to call “the bat- tery detail.” (b) The battery detail, in column of twos, requires ap- proximately 60 yards of road space. It is formed from head to rear in the approximate order in which the personnel com- mences to function during and following a reconnaissance. At the head of the detail are the reconnaissance officer, two scouts, the instrument sergeant and signal sergeant. These, with the bugler and a horseholder, constitute what is known as the “battery commander’s party” (BC Party).* This forms a convenient subdivision of the battery detail to take forward on a reconnaissance for positions, under conditions that make it inadvisable to take forward the entire battery detail. Following the battery commander’s party are the instrument men, then the communications personnel with the reel cart and spring wagon following in rear. A bicycle is included in the equipment of the battery headquarters. (c) The position of the battery detail in column on the march varies : (1) If the battery is acting alone, the battery detail marches at the head of the battery. (2) If the battery forms part of a battalion on a march, in the presence of the enemy, it is usual to assemble all the bat- tery details at the head of the battalion and march them im- mediately in rear of the battalion detail. (3) If marching in a mixed column, and rencontre with the enemy is expected, the battery commander’s detail (or the battery commander’s party thereof) may be placed in the column several *In the BC Party, the reconnaissance officer is a general assistant to the battery commander, particularly for reconnaissance. The in- strument sergeant is the understudy of the reconnaissance officer, commands the battery detail, and is present with the BC Party pri- marily to receive instructions relative to observation, and to assist, if called upon, in the location of observation posts. The signal ser- geant is present to receive early information as to communications to be established, the scouts for reconnaissance and security. IX— 5-7 146 TACTICS AND TECHNIQUE— ARTILLERY hundred yards ahead of the firing battery. This is particularly advisable when it is anticipated that quick action upon the part of the artillery may be required, as it gives the battery detail more time to make the necessary preparations for firing while the battery is moving to its firing position. 6. Battery Reconnaissance. — (a) On a battalion re- connaissance, mounted, the battery commander usually is accompanied by his reconnaissance officer and bugler, the remainder of the battery detail remaining with the bat- talion detail, the movements of which are controlled by the battalion commander. As soon as the battery comman- der has received the necessary orders as to his mission, posi- tion, communications, etc., and leaves the battalion com- mander, he sends for his battery detail, which should be at no great distance, and issues his verbal order. The bat- tery may be sent for either before or after the battery com- mander issues his verbal order, depending upon the time element. The verbal order is issued actually to the recon- naissance officer, instrument sergeant, signal sergeant, and 1st sergeant, but it is advantageous to have all members of the battery detail hear it. Usually, it is the 1st sergeant who rides back to the battery and conveys the verbal order of the battery commander to the senior officer with the fir- ing battery, known as the executive officer. (b) When the battery is -acting alone, the battery re- connaissance is conducted in a similar manner. The bat- tery commander is accompanied by his reconnaissance of- ficer and bugler, or by the entire battery commander’s party. The remainder of the battery detail follows in rear, or on a Rank, at a distance designated by the battery commander, keeping the latter always in sight. The battery follows at a slower gait along the route marked by the battery detail under the direction of the 1st sergeant (see footnote to par. 4). (c) The above paragraphs outline the normal methods of conducting a reconnaissance. The method must be var- ied to suit each particular situation. (d) In this connection, see also Chapter VI. 7. Orders of the Battery Commander. — (a) As soon as the battery commander has completed his reconnais- sance, or has received orders for the occupation of a posi- IX— 7-8 .TACTICAL— TECHNICAL EMPLOYMENT— BATTERY 147 tion selected by his battalion commander, he issues a ver- bal order that should include all of the following items, or such as are essential to the particular situation: 1. Information concerning the enemy and our supporting troops. 2. Mission of the battery. 3. (a) Position of the battery, or of each individual gun. (b) Route to battery position. (c) Reference point. Sector of fire (usually the normal sector). Aiming point. (d) Time battery position is to be occupied. (e) Establishment of observation. (f) Establishment of communications. (g) Liaison with supported troops (when battery is acting alone) . (h) Limbers and combat train. (i) Security and use of machine guns and automatic rifles. 4. Battery aid station. 5. Location of battery commander. As stated in the preceding paragraph, this order is is- sued to the reconnaissance officer, the instrument sergeant, the signal sergeant, the 1st sergeant, and to the executive officer (to the last named usually through the 1st sergeant) . (b) As soon as this order is issued the normal proce- dure is for the 1st sergeant to ride back to the battery, re- port to the executive, transmit to him the battery comman- der’s order, and then guide the battery to the position se- lected, riding ahead with the executive to show him the posi- tions for the guns. As soon as the guns and caissons have been unlimbered, the 1st sergeant posts the limbers. NOTE. — The above is based upon the form for battery orders in use at the Field Artillery School, Fort Sill, Okla. 8. The Firing Battery. — The details in the following discussion apply to light artillery only : the principles apply to all types of artillery that accompany troops in the field. (a) Composition and Formation. — Four gun sections and a caisson section (the fifth section) constitute the fir- ing battery.* The habitual formation before going into a position is in double section column. In this formation the gun sections are formed in column, with the caissons either on the right or left of the guns at one yard interval; one *A section is commanded by a sergeant. A gun section has one gun and one caisson, each trailed behind a limber. A caisson section has two caissons with a limber for each. IX— 8 148 TACTICS AND TECHNIQUE— ARTILLERY caisson of the fifth section is in front and one in rear of the column of gun sections. This formation is called “Formed for action.” (b) Preparation for Action . — When it is but a short distance to the position selected for the battery, and when the ground is not too rough, the command is given: “Pre- pare for action,” or two commands may be combined : “Form and prepare for action.” In preparing for action the breech and muzzle covers are removed, the sights placed in posi- tion, the breech is opened and the bore examined, the ele- vating and traversing mechanism are tested, and, with some guns, the upper and lower shields adjusted in position. (c) Occupation of a Position . — (1) In going into a position, a firing battery may approach the position in double section line from the front or from the rear. The battery is halted on the line selected for the battery position, and the command given: “Action front” or “Action rear” as the case may be. Usually, however, a position is approached in double section column from either flank and the command given: “Ac- tion right (or left).” (2) The above is based upon drill ground maneuver and is the invariable method of occupying a position when maneuvering space is available. When the terrain does not permit of maneu- vering, or when a position must be occupied in the dark, each gun and caisson may be led individually to the emplacement selected and marked for it. This method is also employed for placing heavy guns and howitzers in positions where emplacements must be prepared beforehand. (3) When a light battery is in action, each gun caisson is placed on the left of its piece with not more than one foot be- tween adjacent wheels. The normal interval between guns may be taken as 20 yards muzzle to muzzle, but this interval usually varies and may be reduced to as little as 8 yards or increased to as much as 40 or 50. The caissons of the fifth section are normally placed about 20 yards to the right and left of the flank gun sections and usually a little in rear of the line of guns. In- cluding these flank caissons, a light battery normally occupies a front of approximately 100 yards. (d) The Executive Officer . — Two lieutenants are pro- vided with the firing battery. The senior is “executive of- ficer” or “executive.” The junior is assistant to the exe- cutive. Though the captain usually conducts the fire of his battery, he is seldom in close proximity to the firing position, so that the responsibility for the quick and accurate ser- vice of the guns devolves upon the executive. The principal duties of the executive may be summarized as follows : too yards TACTICAL— TECHNICAL EMPLOYMENT— BATTERY 149 150 TACTICS AND TECHNIQUE— ARTILLERY (1) Usually conducts the firing battery to and establishes it in the firing position. Causes such measures to be taken as will facilitate the rapid opening of accurate fire. Sees to the prepara- tion of all practicable protection for the personnel in addition to that provided by the shields. (2) Exercises immediate command of, or supervision over, the battery in the firing position. (3) Repeats all firing data when the captain is not near enough for the battery to command it by voice. (4) Gives the command for commencing firing whether the captain be at the battery or not. (5) Supervises the resupply of ammunition at the firing bat- tery. (6) Has charge of the replacement of casualties. (e) The assistant to the executive assists in the super- vision of the gun sections, especially when difficulties or errors occur in a gun squad. 9. Battery Combat Train. — (a) The combat train of a battery is normally the “maintenance section” (Table 38W) , and carries no ammunition. However, occasions will arise when the position to be occupied by a battery is so restricted that the fifth section caissons will be detached from the firing battery and placed in the combat train. Un- der conditions of long stabilization, it may be advisable to place all the caissons in the battery combat train, employing trenches or other means for storing the ammunition at the firing position, with as much protection from weather and enemy artillery fire as possible. (b) In the 75-mm. battery (horse-drawn) the transpor- tation with the maintenance section consists of: 1 ration cart. 1 water cart. 1 rolling kitchen. 1 battery wagon, 6-horse. 1 store wagon, 6-horse. 1 spare team (6 horses). The battery wagon and* store wagon carry a large assort- ment of tools and equipment, including those necessary for shoeing horses, repairing harness and carpenter work. Ex- tra wheels, extra harness, and spare parts for the gun mechanism are carried. Witl^ the maintenance section are the mess sergeant, stable sergeant, supply sergeant, cooks, mechanics and other artificers. (c) Normally, the maintenance section remains with the firing battery until the latter is about to go into posi- IX— 9-11 TACTICAL— TECHNICAL EMPLOYMENT— BATTERY 151 tion. The maintenance section then falls behind and goes to the post of the limbers. The battalion commander may combine the maintenance sections of the batteries and have them march together under the command of an officer, or non-commissioned officer. In exceptional cases he may at- tach them temporarily to the battalion combat train. (d) If the battery is acting alone, and extra caissons are furnished the battery from the battalion combat train, these caissons are attached to the battery combat train. 10. Ammunition. — (a) The American caisson (75- mm. Model of 1918) carries 72 rounds of ammunition, the caisson limber 36 rounds, the gun limber 18 rounds. To- tal carried in the battery, 177 rounds per gun. (b) The first ammunition used by a battery is taken from the six caisson chests of the firing battery. This am- munition is replenished by the ammunition in the caissons and limbers of the battalion combat train. When the nature of the action permits, the empty caissons of the firing bat- tery may be replaced by full ones from the combat trains. Except for the two flank caissons, this procedure may inter- fere with the service of the guns, so that ammunition brought forward to the battery position is usually dumped as close to the guns as possible, and carried to the gun posi- tion by the cannoneers. (c) The ammunition in the gun limbers is used only as a last resort. 11. Batteries Employed Independently. — (a) Be- sides accompanying batteries (discussed in Chapter XIII), individual batteries may be detached for employment with small advance or rear guards or with other small forces. The battery commander virtually assumes the functions of a battalion commander with only one battery at his disposal, and the tactical principles involved are the same as dis- cussed for the battalion in the following chapter. (b) The power of heavy materiel, and the less intimate tactical connection required with supported troops, make it possible to employ batteries separately more freely than with light guns and light howitzers ; but the same principle applies to heavy as to light artillery — the tactical unit, the battalion, should be held intact as far as possible. IX— 12-15 152 TACTICS AND TECHNIQUE— ARTILLERY 12. Change of Position. — (a) Moving a battery from one position to another, during an action, is attended with more difficulties as a rule, than movement into an initial position. In addition to being out of action during the move- ment, it takes time for a battery to adjust* itself to a new position. The general rule is to move a battery during an engagement as infrequently as possible, consistent with tac- tical needs and effective firing at reasonable ranges. Advan- tage should be taken of darkness and lulls in the combat to improve artillery positions. This matter is discussed in more detail under the tactical employment of the battalion. (b) In moving a battery from one position to another, the guns should be kept out of action the shortest time pos- sible. For this reason it is bad tactics to start a battery out toward a new position that has not been definitely selected, along a route that has not been thoroughly reconnoitered. At least a preliminary reconnaissance should be made while the battery is still in its old position. Before the battery reaches its new position, communications must be estab- lished and firing data computed, so that the guns may com- mence firing almost as soon as the trails are dropped. This requires rapid action and the best of teamwork on the part of the battery commander and his detail. 13. Communications. — Battery communications are discussed in detail in Chapter VII. 14. Administration and Supply. — In all matters of supply, and in minor matters of administration not involv- ing policy or personnel, the regiment deals direct with the battery. In combat, rations are delivered by the regimental service battery to the position of the limbers, where they are cooked and sent forward in ration carts to the firing bat- teries. In a stabilized situation, the limbers, maintenance sections and combat trains are withdrawn usually well to the rear, out of effective range of the enemy’s light guns. Under such conditions, it is desirable to establish cooking facilities for the men of the firing batteries, somewhere in the vicinity of the battery positions. 15. Conduct of Fire. — (a) The conduct of fire means the control of fire upon any target by communicating the necessary commands to the firing battery. Conduct of fire IX— 15-16 TACTICAL— TECHNICAL EMPLOYMENT— BATTERY 153 is usually a function of the battery commander, but may be delegated to any officer in a position to observe. (b) Conduct of fire should not be confused with “fire direction,” which is a function of the battalion commander. The battalion commander tells the battery commander what targets to fire upon, and the object of the fire, whether de- struction, neutralization, harassing, interdiction, or screen- ing by smoke. He may indicate the hour the fire is to com- mence and the period it is to continue. He may even indi- cate the rate of fire, or limit the number of rounds. This all comes under the category of “fire direction.” As a rule, as much detail as possible is left to the battery com- mander, even the selection of targets within the battery’s normal sector of fire, in a situation where there are fre- quent transient targets, or targets of opportunity. (c) Conduct of fire usually includes selecting the type of ammunition to be used, and the type of fuse; also the method of fire, whether by salvo, volley fire, or volley fire sweeping. These are the usual methods employed in fire for effect.* Zone fire is obtained by using volley fire, or volley fire sweeping, at successive ranges. (d) In observed fire, fire for effect is preceded by fire for adjustment, unless the target has been registered pre- viously. The adjustment should be accomplished quickly in order not to lose the effect of surprise. Rapidity of fire, without accuracy, is unprofitable ; on the other hand, accur- acy slowly obtained frequently results in lack of effect, be- cause the enemy will have time to shelter himself from the fire. The ideal is accuracy combined with rapidity, in a short intense burst of fire. 16 . Observation of Fire. — (a) Generally speaking, the most dependable means of conducting observed fire is by terrestrial observation. Balloon observation is fre- quently as efficient or more so. Adjustment with airplane observation is slower and more subject to interruption, but *A battery salvo consists of one round fired by each gun at in- tervals of three seconds or more. In volley fire, each gun fires a designated number of rounds in rapid succession. Volley fire sweep- ing is the same, except that after each round the gun is traversed to move the point of impact to the left 20 to 25 yards. IX— 16-17 154 TACTICS AND TECHNIQUE— ARTILLERY is invaluable for adjustment on targets when terrestrial or balloon observation is not possible or very poor. (b) Terrestrial observation should be provided near enough to the bring battery to insure efficient and uninter- rupted communication. It is an additional advantage to have the battery position visible from the observation post. With the observing instruments provided, proximity to the front lines is not essential except in cases in which the safety of friendly troops or long ranges are involved. It is well, however, to push observation posts as far forward as conditions admit. Frequently the best observation may be had from a point in rear of a firing battery. (c) In country where .observation is considerably re- stricted, a battery seldom has one fixed observation post, but changes its point of observation for almost every tar- get that is fired upon. For the reason that animate tar- gets for artillery are the exception rather than the rule in modern warfare, and that defensive works are carefully con- cealed or camouflaged, artillery targets usually are limited to points on the terrain where the enemy is known or sus- pected to be. (d) Battery observation posts are seldom manned after dark or during weather that makes observation impossible, though battery observation posts may be established under these conditions for the sole purpose of watching for pyro- technic signals. By special arrangement, in stabilized sit- uations, battalion observation posts may be employed by the batteries for registration or special adjustments, establish- ing communication between the firing battery and the bat- talion observation post usually through the battalion tele- phone net. (e) The technical relation of observation to the con- duct of fire is discussed in Chapter V. 17. Map Firing. — (a) The technical employment of map of topographic firing is discussed in Chapter V. It is of immense importance for firing upon targets when observed fire is impracticable. It may be employed at night or in fog or rain, but should never take the place of observed fire when the latter is feasible. The object of fire adjustment is to place the center of impact as close to the target as IX— 17 TACTICAL— TECHNICAL EMPLOYMENT— BATTERY 155 possible. In map firing, an attempt to place the center of impact upon the target is made by calculations, the accur- acy of which usually cannot be verified during the progress of the shoot. On the other hand, in observed fire the center of impact generally may be placed very close to the target. (b) The most accurate map firing is based upon a pre- liminary registration by observed fire with a particular lot of ammunition, upon some well-defined objective within the enemy's lines. A transposition of the trajectory then is made to the desired target, based upon its difference in top- ographic location with respect to the registration point and the battery position (see Chapter V). Without pre- liminary registration, map firing seldom can be depended upon for greater effect than neutralization, no matter how accurate the maps and meteorological, data may be. (c) Map firing, and the topographic preparation of firing data for observed fire, must not be confused. In the latter, the map or other topographic means are employed for calculating the firing data for the first shot on a parti- cular target. After the first shot, salvo or volley is fired, and its impact observed, corrections are made in the usual manner until the correct data are determined. The topo- graphic preparation of firing data gained great importance during The World War, and the fire efficiency of any battery will be increased greatly by knowing its topographic loca- tion with respect to its observation post and its targets. If this cannot be determined by means of an accurate map, the necessary locations with respect to each other may be deter- mined by means of triangulation and traverses made by the instrument men of the battery detail under the direction of the reconnaissance officer. X— 1-2 CHAPTER X Tactical Employment of the Battalion Paragraphs Light, Medium and Heavy Artillery Battalions 1 General Functions of the Battalion 2 General Functions of the Battalion Commander 3 Keeping the Battalion Intact 4 Formations of Battalion * 5 Reconnaissance (See also Chapter VI) 6 Selection of Positions (See also Chapter VI) 7 Security 8 Communication 9 Observation 10 Ammunition Supply 11 Changes of Position 12 Supporting the Infantry __ 13 Battalion Orders 14 Conditions Affecting the Efficacy of Battalion Employment 15 Offensive Employment r 16 Defensive Employment 17 Disposition of the Batteries 18 Disposition of Combat Train (See Chapter VI) 19 Provisional Battalion 20 1. Light, Medium and Heavy Artillery Battalions. — The tactical employment of light, medium and heavy ar- tillery battalions is so similar that it is deemed unnecessary to consider the three types of artillery separately. The following discussion, therefore, may be taken as applica- ble to either light, medium or heavy artillery, unless dis- tinctions are stated specifically. 2. General Functions of the Battalion. — The bat- talion is a unit for the immediate command of a number of batteries ; it is, above all a tactical unit. The functions of the battery and the battalion are distinct, and are best ex- plained by repeating the definitions of the terms conduct of fire and fire direction as used in the artillery. Conduct of fire is “the employment of the technical means necessary to cause fire of the desired nature to be brought to bear upon the target.” Fire direction is “the tactical direction of one or more fire units with a view of bringing their fire to bear at the right place at the right time.” Conduct of fire “is the function of battery commanders ;” fire direction “is the 156 X— 2-5 TACTICAL EMPLOYMENT OF BATTALION 157 function of battalion commanders.” Conduct of fire by a battalion commander is very rare, and endeavor should be made to have such tactical dispositions that this will be un- necessary. 3. General Functions of the Battalion Com- mander. — The battalion commander devotes his efforts mainly to : Keeping in touch with the tactical situation of our own and hostile troops. The advance selection and preparation of areas or positions to be occupied by his batteries, and the routes thereto, in con- formity to orders received from higher authority. The assignment of clear and specific tasks to his batteries in furtherance of the tactical plan of the commander. The supervision of ammunition supply and expenditure. The supervision and assistance of battery commanders in their execution of assigned missions, by giving additional infor- mation from time to time or by corrective measures when clearly necessary. He avoids interfering with battery commanders, but allows them the fullest possible initiative consistent with his responsibility for the results accomplished. 4. Keeping the Battalion Intact. — Since the bat- talion is the smallest distinctly tactical unit in the artillery, it preferably should be kept together and well in hand, in order that its maximum effectiveness may be developed. 5. Formations of Battalion. — (a) On the March . — The marching formation of the battalion is the section col- umn. The major and his headquarters are at the head of the column. Under a tactical situation, the batteries habi- tually march immediately in rear of the battalion headquar- ters. The battalion combat train marches in rear of the column of firing batteries, often separated therefrom by units of other arms. A corporal of the combat train re- ports to the major as agent, taking with him such additional men as may be required for this duty. If action is imminent, the major may direct the bat- tery commanders, with their details, to march immediately in rear of his own headquarters. The major himself, with a small staff, may march ahead of his column, particularly with his regimental commander, if the regiment is together, or with the infantry commander with whom he is directly associated. This subject is covered more in detail in Chap- ter XII. X— 5-7 158 TACTICS AND TECHNIQUE— ARTILLERY (b) In Action . — For action, the firing batteries and battalion combat train are posted in positions designated by the major. The major selects his post, having in view effective command of his batteries as well as proximity to the infantry commander with whom he is directly asso- ciated. If both of these considerations can be fulfilled by the same location, it is ideal ; if this is not possible, the major must choose for sure and effective command of his batteries, making the communication with the infantry commander as short and reliable as possible. 6. Reconnaissance. — (a) Reconnaissance is one of the most important duties of the battalion commander, and enters into most of the functions of the battalion in a tac- tical situation. Reconnaissance is necessary in selecting routes, in occupying or changing position, in the selection of a position, and for the immediate security of the battalion in action or on the march. The battalion headquarters per- sonnel is reasonably complete for this purpose. Although exceptional cases may necessitate augmenting the battalion headquarters personnel from the battery details, this prac- tice is to be avoided; battery details should be left for the exclusive use of battery commanders. The basic object of reconnaissance is to insure the prompt and orderly carrying out of assigned missions by the guns themselves; it follows that reconnaissance must be timely and must be made suf- ficiently in acl ance to insure that the guns are not delayed or hampered. (b) The reconnaissance of a route is made in the same manner as for the battery. The Signal Corporal No. 1 is charged with the details of marking the route selected. There is no personnel provided exclusively for marking the route. In the selection of the route, the scouts are employed to examine and report upon various prospective routes and similar missions. 7. Selection of Positions. — In the reconnaissance of positions, the major examines the terrain in view of the orders he has received, making such use of his staff, parti- cularly the reconnaissance officer, as is expedient. He se- lects positions for the batteries with an exactness depending on the time available. He selects a post for the battalion TACTICAL EMPLOYMENT OF BATTALION 159 combat train, or merely indicates its general location and leaves its selection to the commander of the combat train. The combat train agent usually accompanies the battalion commander on his reconnaissance. The major selects his own post early and takes prompt measures to observe the hostile dispositions and movements. He may be accom- panied on his reconnaissance by the battery commanders, in which case he assigns them positions as selected. If the battery commanders or battery reconnaissance officers are not present, the major communicates, by means of the bat- tery agents, the necessary orders for the occupation of the position selected, or he may send for the battery comman- ders and communicate his orders in person, either during or upon the completion of his reconnaissance. The major’s reconnaissance should be completed sufficiently early to ena- ble the battery commanders to make their own reconnais- sance without delaying the batteries. 8. Security. — Security on the march and in action is provided by the major by disposing scouts so as to guard against surprise by small hostile parties. He may assign missions to batteries in this connection. 9. Communication. — See Chapter VII. 10. Observation. — The major habitually establishes an observation post. Depending on the situation, this post may be at or near the battalion command post ; in any event, the two posts are connected by telephone. The principal needs of a battalion observation post are for information and fire direction. By special arrangement, in stabilized situations, battalion observation posts may be employed by the batteries for registration or special adjustments. 11. Ammunition Supply. — The ammunition supply is from the rear forward; the artillery brigade ammunition train supplies the battalion combat train, the combat trains supply the batteries by exchanging caissons or transferring ammunition. One platoon of the combat train usually sup- plies a particular battery, though exceptions to this proce- dure may be necessary. The commander of the battalion combat train directs the ammunition supply of all of the batteries. When a position for action has been selected, the combat train agent with the major operates between the X— 11-12 160 TACTICS AND TECHNIQUE— ARTILLERY combat train and the major, keeping the latter informed as to the state of ammunition supply, and insuring that the necessary ammunition is brought up. Batteries habitually call for ammunition directly upon the combat train, the major supervising both the consumption and supply. 12. Changes of Position. — (a) The initial occupation of a position for action, either on the offensive or defensive, ordinarily is relatively simple as compared with a change of position during an action. The latter, under certain con- ditions may be hazardous, and, in nearly all cases, speed is essential in order that the artillery may be out of action a minimum of time. In retiring or advancing a given distance, the fewer positions occupied the longer the pieces are in ac- tion, since there is always a certain loss of time in leaving or occupying a position and in organizing it. In an advance, how- ever, the use of but a few positions results in the range used just before changing position being very long, which in- volves inaccuracy of fire, long communications, consequent difficulty in supporting the infantry, and more distant ob- servation. In retiring, similar difficulties arise, due to the long range used when a position is first occupied. Thus there are considerations for and against frequent changes of position, and the procedure actually used must be a com- promise between these conflicting considerations, based on the situation ; no rigid rule can be laid down. The disadvan- tages of frequent changes of position can be lessened by rapid and skillful selection and occupation of position. Full advantage should be taken of lulls in the action or of dark- ness to improve the artillery dispositions. (b) It is obviously desirable to effect changes of posi- tion by echelon, in order that the infantry may have some artillery support at all times. In the case of a small artil- lery force, say a battalion, changes of position by battery practically always are advisable. In the case of a regi- ment or larger artillery unit, the tendency should be toward changing position by a battalion at a time. This is primarily because, as previously stated, the battalion is the smallest distinctly tactical unit and develops its maximum effective- ness only when it is well in hand as far as command is con- cerned. If a battery of a battalion changes position, it tern- X— 12-13 TACTICAL EMPLOYMENT OF BATTALION 161 porarily leaves the control of the major; the loss of control is increased when the second battery changes; and if the progress of the action is rapid, it is doubtful whether the battalion thereafter will be in action as a unit. In many sit- uations it will be practicable for the support missions of a battalion to be taken over by another battalion sufficiently to permit changes of position to be made by battalion, in which case the battalion is at all times entirely under the control of the major. 13. Supporting the Infantry. — (a) The artillery battalion is an important unit in supporting the infantry. Successful support is dependent on continuous knowledge of the situation and needs of the supported infantry. This information is obtained by the artillery battalion keeping in close touch with the command posts of the supported in- fantry, either by the various means of communication or by the actual presence of artillery officers at these command posts, or both. The artillery habitually maintains its own means of communication for this purpose, using the infan- try communications only in emergency. These artillery communications are available for use by the infantry in case their own means are interrupted. (b) As already stated, the major takes his command post in action with the supporting infantry commander, provided he can command his guns effectively from this post, otherwise he sends a liaison officer to the infantry command post. In case the artillery battalion supports an infantry regiment, the major’s endeavor would be to post himself with the infantry regimental commander. But habitually it would be incumbent on the major to establish direct artillery communication with the front line infantry battalions, independently of infantry communications. The major’s staff includes a liaison officer. If the major were with the infantry regimental commander, the liaison officer would be sent to the front line battalion commander ; if there were two front line battalions, it would be proper to detail an additional liaison officer. Similarly, if the major could not be with the infantry regimental commander, an addi- tional liaison officer would be necessary. The liaison officer is accompanied by certain enlisted personnel, not provided x— 13-14 162 TACTICS AND TECHNIQUE— ARTILLERY specifically, including usually a non-commissioned officer as assistant and relief and the necessary personnel for com- munication. (c) The liaison officer may be said to have a triple role. First, he transmits the needs of the infantry to the major and acts as advisor to the infantry commander on artillery matters. Second, he gathers artillery intelligence data. Third, he keeps himself prepared to assist the artil- lery in the identification and verification of targets and in the actual conduct of fire that cannot be handled by battery observation. The first named function is the primary and most important one. The liaison officer joins the infantry unit to which assigned as early as possible and remains with it during the continuance of the arrangement which caused his assignment. The periodical but not too frequent relief of liaison officers is advisable, in order that they may be in close touch with the artillery which they represent. Liaison officers must be active, and alert, professionally capable, tactful, and personally acceptable to the infantry commanders to whom assigned. (d) Batteries ordinarily do not establish relations with the supported infantry, though this may be necessary in some situations. Heavy artillery battalions, as a rule, do not maintain separate direct communications with the in- fantry in this manner, but utilize, when necessary those of the most convenient light artillery battalion. (e) Regardless of whether the major is with the sup- ported infantry commander, and whether the artillery bat- talion is in support or attached, the major must maintain active personal touch with the supported infantry com- mander, advise him on artillery matters, and endeavor to meet his wishes in every way possible; this perhaps is the most important single element in their successful coopera- tion. 14. Battalion Orders. — The orders of the major are usually verbal; frequently they are not issued formally or to all battery commanders at the same time, though this is desirable. Verbal orders by the major may be accom- panied by tables, marked maps, or charts prepared by higher artillery or other commanders. The major's orders, verbal X — 14-15 TACTICAL EMPLOYMENT OF BATTALION 16? or written, follow the form prescribed for field orders in general. The following points, if pertinent in the particu- lar situation, would be covered in paragraph 3, under the paragraphs for the individual batteries or in subparagraph (x): Positions to be occupied. Routes and order of march. Missions, including sectors of fire, special fire, reference points, etc. Time for occupying position and of opening fire. Instructions as to observation. Cooperation with infantry or other elements without the bat- talion. Organization of positions, security, dispositions of machine guns and automatics. Instructions as to the limbers, if any are given. Other necessary instructions. The combat train and sanitary personnel are covered in paragraph 4, which may contain, also, instructions to the field train if with the battalion, and as to supply, cooking, water, etc. Communications and command are covered in paragraph 5 in the usual manner. 15. Conditions Affecting the Efficacy of Battal- ion Employment. — (a) The great power of the battalion, its abundant technical means, its numerous special person- nel, and its mobility, make it a unit well adapted to meet the changing requirements of the various technical situa- tions which may arise. The burden of making the battalion thoroughly effective falls principally on the major; if he fails to grasp the situation properly, much of the power of the battalion will be lost. (b) The amount of latitude and initiative allowed the major in handling his battalion tactically, varies with the size of the artillery command and with the situation. If the battalion were the only artillery with, say, an advance guard, the major, in conjunction with the advance guard commander, could exercise a maximum of initiative and would have a corresponding responsibility. When acting as an element of an artillery brigade, the missions of the battalion ordinarily would be much more circumscribed. In the more open and rapidly moving situations, the major might have wide responsibility, while, in a stabilized situa- tion, his missions probably would be prescribed within nar- row limits by higher authority. X— 16 164 TACTICS AND TECHNIQUE— ARTILLERY 16. Offensive Employment. — (a) In offensive ac- tions, the character of the fire of the battalion may be either of two classes : first, that according to a prearranged sched- ule of time and objectives, such as barrages or succes- sive concentrations; and second, that on objectives actually encountered by the infantry as it advances, calling for off- hand artillery support. In the first case, the battalion or- dinarily receives detailed instructions from higher author- ity and acts largely as an executive agency in carrying out these instructions. Situations may arise in this case, how- ever, which were not foreseen and which call for prompt action on the part of the local infantry commander and the major. In the second class of action, the prior dispositions of the major must be confined largely to the assignment of zones of action to the batteries, the thorough registration of the terrain, as far as the situation permits, and the establish- ment of good observation and reliable communications with the infantry. Then, when the infantry actually calls for fire, it will be delivered with a maximum of promptness. Even in this case, the major, in cooperation with the sup- ported infantry commander, should select certain points as most likely to offer resistance, and cause fire to be deliv- ered on these points until the resistance is located more de- finitely, subject to the limitations of ammunition available. The battalion should not be idle for lack of a definite tar- get. The responsibility for this rests with the major and his battery commanders and not with the infantry com- mander. Frequently, on account of lack of time or com- munications to consult with the infantry, the major must act according to his best judgment based on what he sees, or on his batter knowledge of what the artillery can do. (b) In such cases of offhand artillery support, a trou- blesome feature is the time the fire is to continue on a given point. A number of methods are feasible. The infantry may call for fire beginning and ending at certain times, ar- ranged in consultation with the artillery ; or the call may be for fire of a fixed duration to be delivered as soon as possi- ble ; or the fire may be delivered at a given time or as soon as possible and lifted or terminated upon signal (usually pyrotechnic) by the assault unit or artillery personnel with X— 16-17 TACTICAL EMPLOYMENT OF BATTALION 165 it ; or the fire may be placed and lifted by means of the ar- tillery observation. None of these methods can be stated as the most effective; that by artillery observation is the method to be preferred in all cases when observation is possible and is coupled with good communications. It has been suggested that conventional combinations of fire sup- port be arranged between the infantry and artillery and be designated by number or otherwise. This would have the advantage of simplifying messages calling for artillery sup- port, and of habituating the infantry to certain typical forms of fire support. But the necessity for close coopera- tion and communication between the infantry and artillery, and for prompt response by the artillery, still would be present. (c) It is evident that offhand artillery support calls for more advanced positions of the artillery than prear- ranged support; this is particularly true of rapidly moving situations in which elaborate communications are not feasi- ble ; the extreme case is that of accompanying batteries and accompanying guns. 17. Defensive Employment. — In defensive situa- tions, prearranged artillery support must be worked out in great detail; provision must be made also for offhand sup- port. While, in an organized defensive position, the orders from higher authority ordinarily would prescribe in some detail the missions of the artillery battalion, the major, nev- ertheless, has important duties in this connection. He, and the supported infantry commander, must study the ground together and in detail, and arrange the exact points on which the artillery support may be placed to best advantage. It is important that the dispositions of the other auxiliary wea!pons be considered in this connection. Provision should be made for the various contingencies that can be antici- pated. When time permits, the dispositions made should be tested and practiced by calls from the infantry and such responses from the artillery as may be practicable. The major must give careful attention to the organization of his observation, a factor of prime importance on the de- fensive. X — 18-20 166 TACTICS AND TECHNIQUE— ARTILLERY 18. Disposition of the Batteries. — The battery posi- tions, on the defensive, ordinarily differ materially from those on the offensive. On the offensive, the batteries us- ually are well advanced consistent with concealment, and relatively close together. A defensive position has depth, and artillery support must be more or less continuously available throughout this depth. Rarely will a single posi- tion for the battalion fulfill these conditions, and the echel- onment of the battalion in depth usually is necessary. It is desirable that the maximum fire power be developed in front of the foremost element of the position (outpost sys- tem), but it is essential that this maximum power also be developed in defense of the main defensive position. These are conflicting considerations, since, frequently, positions in rear of the main defensive position cannot reach the fore- most elements of the outpost system. The solution lies in placing certain batteries, rarely complete battalions, in ad- vance of the main defensive position, and making careful arrangements for their timely withdrawal in rear of this position. The number of batteries which can be placed ini- tially in advance of the main defensive position, depends on the terrain, particularly the routes available for movement of artillery, and the situation; ordinarily it will not exceed one battery per battalion, exceptionally two per light artil- lery battalion. Positions in rear of the main defensive posi- tion may be well advanced with respect to this position, with the batteries of the battalion reasonably close together. 19. Disposition of the Combat Train. — See Chapter VI. 20. Provisional Battalion. — In some cases, particu- larly in view of an attack, the supporting artillery is rein- forced, sometimes by an equal amount. Rather than dis- rupt the existing assignments, it is customary to attach the reinforcing artillery by battalion or battery units to the artillery already in position. A battalion thus may be rein- forced by a battalion or several batteries. The temporary unit thus formed sometimes is called a provisional battalion. Its tactical functions are the same as the battalion, although a re-distribution of missions will be necessary. The com- X— 20 TACTICAL EMPLOYMENT OF BATTALION 167 mand generally remains with the major already in position, regardless of the relative rank of the two majors, unless the supported infantry is relieved by the infantry of the rein- forcing artillery, in which case the command of the provi- sional battalion may pass to the incoming major. XI— 1-2 CHAPTER XI Tactical Employment of the Regiment and Brigade Paragraphs Section I. — The Regiment 1-15 Section II. — The Artillery Brigade 16-22 Section I The Regiment Paragraphs Composition 1 General Functions 2 The Rear Echelon 3 The Regiment on the March 4 Disposition of the Regiment in Action 5 Sectors of Fire 6 Troops to be Supported 7 Enemy Batteries 8 Movements from Position to Position 9 Regimental Headquarters 10 The Service Battery 11 Reconnaissance (See also Chapter VI) 12 Communications (See also Chapter VII) 13 Observation 14 Regimental Orders 15 1. Composition. — A regiment of field artillery, in our service, is organized for the use in battle of 24 guns or howit- zers. Its composition, for the various types of materiel, is discussed in Chapter I. Full information as to its or- ganization is to be derived from a study of the Tables of Organization. 2. General Functions. — (a) The artillery regiment is both an administrative and a tactical unit. (b) To the colonel falls the broad direction of tactical employment, based on orders from higher sources, drawn to secure coordination and cooperation with the troops that the regiment is to support. The details of tactical employ- ment are handled by the executive officer who apportions the 168 XI— 2 THE REGIMENT 169 tasks, as they belong, to the various sections of the regi- mental headquarters, and then follows up their development in order to see that proper coordination is actually secured within the working time available. Thus the regimental commander is freed to make decisions on important matters and to effect a more intimate personal liaison with his own artillery commander and with the commander of troops that his regiment supports. (c) The principal functions of the regimental comman- der and his headquarters may be summarized as follows : (1) Tactical control over the battalions, in the allotment of missions to carry out the tasks assigned to the regiment; desig- nation of the location of battalion positions, sectors to be cov- ered, troops to be supported, enemy batteries to be neutralized or destroyed, other special objects of attack, and movements to be made from one position to another. (2) Intelligence. Gathering information of technical or tac- tical value from the battalions and from all other sources, and disseminating this information wherever it can be employed. Distribution of maps within the regiment. (3) Connection with supported troops . — (a) The regimen- tal commander is usually able to devote more personal time and effort to this important detail, tactically, than can his battalion commanders, whose efforts will largely be absorbed, in battle, in fire direction. In the infantry division, this tactical connec- tion, by the light artillery regimental commander, is made mainly with an infantry brigade, but may extend to the commanders of the infantry regiments which his battalions are supporting. The most cordial relations and mutual understanding between in- fantry and supporting light artillery should be fostered by as- sociating 1 as far as possible the same units in both training and combat. (b) When it is necessary to reinforce the light artil- lery which is supporting an infantry unit, the reinforcing artillery is frequently included in a provisional battalion, or ‘‘groupment/’ with the artillery already assigned to the support of the infantry. (4) Communications. General supervision over signal com- munications throughout the regiment, lending as much assis- tance as possible toward the maintenance thereof by the battal- ions. (5) Ammunition Supply. General supervision over ammu- nition supply and expenditures. (6) Supply, Replacements, Evacuation and Burials. A close supervision over the supply of rations, equipment and clothing; the distribution of replacement personnel; the replacement and repair of disabled guns and other important materiel; the evacu- ation and replacement of animals and motor vehicles; care of the wounded and burial of the dead. (7) Training of the Headquarters Company, so as to insure uniformity in the work of technical personnel. (8) Morale and Efficiency. As an administrator, the regi- mental commander is responsible for the morale and esprit de corps of the regiment, for the assignment and transfer of officers XI— 2-4 170 TACTICS AND TECHNIQUE— ARTILLERY from one unit to another, for war diaries, field orders and other records. He is responsible for the efficiency of his battalions and for the establishment of uniform methods and policies that will make his regiment a coordinated whole. In this connection he should give his battalion commanders as much latitude and play of initiative as possible; but, finding one battalion less re- sourceful or less efficient than another, he should strive to bring it up to a higher standard. 3. The Rear Echelon. — (a) Where battle movement becomes sluggish, it is manifest that, automatically, a sys- tem will be evolved which relegates to more or less safe distances those whose presence is not actually needed in the combat lines. The establishment of a local colony of these non-combatants, which was thus brought into being during The World War, was termed the “rear echelon.” (b) It grew around the service battery for conven- ience. Here, most of the administrative details were at- tended to, and it became a location for general repairs that could be completed within the regiment and a place of collection for the sick and wounded animals that did not require evacuation. Here, also, were to be found such detachments and vehicles of the batteries ais were not needed with the firing batteries and combat trains. Though its present development is an outgrowth of conditions our army met in Europe, a similar procedure in essence must be expected in the future in moving situations, if for no other purpose than clearing the battle lines of those whose important duties are not actual combat. 4. The Regiment on the March.— Though a regiment of artillery frequently marches in one column, the battalion is essentially the marching unit. When marching with other troops’, and an engagement is imminent, the combat trains may be a mile or more in rear of the regiment, and small detachments of regimental and battalion headquar- ters, and of the battery details, are pushed ahead of the regiment in the column, in order to insure an early recon- naissance. With an engagement impending, the regimental commander of the leading artillery regiment in the column, in most cases, would be with the commander of the infan- try brigade that his regiment is to support. It would be desirable for him to have his battalion commanders with him or near at hand. XI— 5 THE REGIMENT 171 5. Disposition of the Regiment in Action. — (a) Tire regimental commander often has opportunities to ex- hibit tactical skill. Such opportunities are disclosed in his reconnaissance. His subsequent orders should be such as to insure maximum fire power from his battalions, efficient communication therewith, and subsequent surety of com- mand. (b) Excessive dispersion of the battalions should be avoided in order to conserve the integrity of communica- tion, dependent upon the modifying influence of the selec- tion of the most favorable localities for normal and even- tual fire support. (c) The terrain and tactical situation always determine the local employment of the artillery, but there are general principles which will apply. Offensively, it is advanta- geous to select positions far forward in order that the battalions may continue their fire support as long as pos- sible, without interruption, until forward displacement be- comes necessary. Due to the flat trajectory of the 75-mm. gun, it cannot fire effectively from a position of flash de- filade at targets close to the guns. Since the masked posi- tion is usual, the guns must not be placed too close to their targets. Moreover, difficulties in entering advanced posi- tions in daylight, without undue exposure and the atten- dant casualties, always must receive the most careful con- sideration. This minimum range, to initial targets in the enemy’s front line, can hardly be expected to be found much less than the elastic limit of 1500 yards. Reduced charges, with their more curved trajectory, allow the enemy to be approached several hundred yards closer, whence positions may be still selected for flash defilade if the terrain per- mits. The difficulties of unobserved entry (except at night) , and the fact that such positions are well within the limits of machine gun and small arms fire, preclude the idea of their occupation, however. (d) As for the medium howitzer, its approach within the same distance is even more dangerous (except at night or other peculiarly advantageous conditions, such as very favorable terrain for an approach) since it offers a larger and more slowly moving target. Due to its very curved XI— 5 172 TACTICS AND TECHNIQUE— ARTILLERY trajectory however, it may find more readily a suitable mask. (e) Based on these considerations, we may expect, roughly, the regimental commander to limit his initial re- connaissance for battalion locations to positions at a greater distance than 1500 yards from the enemy. (f) Looking at the situation from the other viewpoint, i.e., ease of fire direction, fire control, and the technique of the battery, there are many advantages to be found in posi- tions farther to the rear. In and around 3000 yards from the hostile lines, it is easy, in average terrain, to find posi- tions that give reasonable cover ; and, even if the observing station necessarily is situated in the immediate vicinity of the guns, the range is such that excellent observation often can be obtained with the telescopic instruments in use. So it is safe to assume that the regimental comman- der generally will select localities for his battalions within the very elastic limits of from 1500 to 3000 yards from the enemy front lines, when practicable. (g) The next point to consider is the character of fire support that each battalion will be called upon to render, and, having determined it, to locate the battalions accord- ingly. Since every tactical situation may present more than a single solution, it is obviously impossible to refer to but a few brief points that may be illustrated herewith. They should, it is believed, indicate that grave tactical responsi- bility falls on the regimental commander. (1) 1st Case. — Open Warfare. — Contact has been made and deployment effected. Line of departure from AB at a desig- nated time. The advance is along one side of a river valley. The spurs at right angles to the general flow of the river and found between the smaller lateral tributaries, form a series of long ridges which afford the artillery cover and observation sta- tions near the guns. Suppose, in this case, the colonel makes an assignment of battalion locations well to the front, broad in extent and slight in depth, which in effect puts the regiment in line of battalions; we will have the situation illustrated as “1st Case.” (a) Advantages . — Battalions being well forward, effec- tive fire power remains longest before forward displace- ment is required. If the position is likely to be occupied some hours, or during the night, a single regimental ammunition distribu- ting point may be so conveniently located, sometimes, as to permit, temporarily, direct supply to batteries without the intermediate need of combat trains. XI— 5 THE REGIMENT 173 The locations may be such that the regimental com- mander can be in close touch with the infantry brigade com- mander, and, at the same time, occupy an observing station not distant from those of the battalion commanders, and see things, tactically, as they see them. Due to the slight depth of the formation, wire is saved as well as the time necessary to lay it. Data computed for one battery can be quickly trans- posed for use in an adjacent battery. It facilitates a forward displacement by battalion in line, thus limiting exposure on ridges to a minimum of time. Wide lateral dispersion of the batteries will facilitate at- tack of hostile targets by allowing them the minimum of dead space. (b) Disadvantages . — Enemy counter battery fire can be readily shifted to an adjacent battery after once effec- tively laid. Case 174 TACTICS AND TECHNIQUE— ARTILLERY If the enemy uses diagonal fire he is not obliged to make an exact range adjustment. A change in deflection from time to time will insure hits from directions most disconcert- ing to the cannoneers. If a flank movement be made, to reach a longitudinal road for a forward move, and the battalions are restricted to narrow passages when moving out from cover, a single carriage in trouble may delay an appreciable part of the regiment. (c) Simple orders place the regiment in such a forma- tion. For instance: “Location for regiment, immediately north of grid line 349; 1st Battalion east of such point (or line), and 2d Battalion west of the same.” (2) 2d Case. — Open Warfare. — Contact established and an advance ordered within limits indicated. A natural feature of the terrain at A indicates the probability of our 2d Infantry advance being slowed at that point. It is so close to the route of advance of the 1st Infantry that the advance of the latter also 2° Case XI— 5 THE REGIMENT 175 will be delayed. For the actual support of the 1st Infantry, it may be better, for a time, to fire on a target in the zone of ad- vance of the 2d Infantry. The responsibility for the locations of the battalions, so they may properly cooperate in this task, is one that falls to the colonel of the 1st Field Artillery, which is supporting the 1st Brigade. The battalions preferably are placed well to the front, wide apart, and on either side of the strong terrain feature to be attacked. This insures diagonal fire on all parts of the target, the possibility of both flank and diagonal fire simultaneously on some parts of the target, and the smallest pos- sible dead space in rear of the target. It also aids our infantry in their flank attacks. (3) 3d Case. — Open Warfare. — Assume that the tactical conditions are such that it will be desirable, in an attack, for a certain battalion to be displaced forward rapidly via a longi- tudinal road, where the terrain features are such as to prevent any but short movements off the road. It is evident that the regimental commander can indicate the position in such a manner that each battery in the battalion probably will be able to have its 3 d Case XI— 5 176 TACTICS AND TECHNIQUE— ARTILLERY own route to the longitudinal road and thus prevent a single battery in misfortune holding up the access of the remaining batteries to the route forward. Thus it is seen, even before any displacement tables are issued, the regimental commander has in his power the opportunity to select the battalion locations so that, if rapid displacement forward be the paramount considera- tion, he can force, within limits, his battalions taking up suitable formations without giving lengthy orders on the subject. In this case he would indicate a deep, narrow area adjacent to the route of advance. (4) 4th Case . — The cases so far illustrated have presupposed conditions under which the battalions can render the best sup- port to their infantry by operating within their respective sec- tors. This is not always possible for the best fire effect. En- filade fire is particularly valuable. Aside from its effect on mor- ale it has the advantage that an error in range will still produce results. Probable errors in deflection are always small. In the 4 th Case XI— 5 THE REGIMENT 177 attack of a prepared position or defensive zone, enfilade fire is sought. In the case in question, assume the attack of the front line of a prepared position. The 1st Battalion 1st Field Artillery sup- ports the 1st Infantry and the 2d Battalion 1st Field Artillery supports the 2d Infantry. Enfilade fire is desirable initially. This can be arranged by having the 1st Battalion, 1st Field Artillery, placed in the 2d Infantry subsector and the 2d Battalion 1st Field Artillery placed in the 1st Infantry subsector; or, the 1st Battalion, 1st Field Artillery may remain in its own subsector and support the 2d Infantry up to a stated time or until it reaches a certain line, and the 2d Battalion, 1st Field Artillery may take similar action in regard to the infantry it is to support. These dispositions sometimes might be required, in order to gain maximum fire effect; tactically they present weaknesses which must be considered. These weaknesses are: (a) When the battalions are placed in opposite sub- sectors, the battalion commander, in order to remain near his battalion, cannot also be near the commander of the unit that he supports, and is dependent on long lines to his liaison officer, which may be shot away at any time. (b) The supporting of one unit up to a certain time or place, followed by a change in the supporting units, is weak in that the advance may not meet the exact schedule as planned, and the full support depends on the initial plans being realized. The initial situation is best controlled by progressive concentrations or similar action but these may become so restrictive in their application that they do not meet emergencies. (5) 5th Case . — Assume a stabilized situation as outlined in the sketch. The artillery regiment is to support a holding at- tack made by the right infantry brigade, while the left infantry brigade is advanced. Indications are that a hostile counter at- tack may be launched from the direction indicated by the arrows. One battalion must be located so as to fire as far to the north as possible and one must respond to eventual calls in the left brigade sector. How may the artillery regimental commander meet this situation in locating his battalions and at the same time support the infantry brigade with which associated, in case of a counter attack, assuming the general arrangement of sub- sectors as shown on the sketch? It is evident that, if both battalions of light artillery are placed in the northern part of the sector, they may be subject to enfilade fire and will be poorly disposed to meet a possible enemy counter attack. By locating the forward battalion to give fire as far to the north as possible, and also to give eventual fire in the left brigade sector, one condi- tion is met; the rear battalion of field artillery will be available to meet a counter attack and can assist the advanced battalion in fire delivered to the north. The loss in range for this latter contingency can be compensated for, in a large degree, by the use of a supply of type “D” shells for the rear battalion. (These shells give additional range.) (h) The above are but a few situations to emphasize the fact that the regimental commander does and must exercise important tactical direction over his battalions. These tactical opportunities are met more frequently in XI— 5 178 TACTICS AND TECHNIQUE— ARTILLERY 5 th Case \ open warfare situations because of greater dispersion; but, since these opportunities are often fleeting, due to the com- bination of the elements of mobility and limited time, much training is required in this branch of the art, not only to rqcognize the situation when it appears, but also promptly to take advantage of the opportunity offered. In general, XI— 5-6 THE REGIMENT 179 the principles applicable to moving situations also are ap- plied to the stabilized situations, the difference being that, in the latter case, there is usually much more time for* a mechanical solution to be effected and it is, in consequence, an easier, but more detailed problem. (i) The most favored positions for the medium howit- zer battalions normally will be somewhat farther to the rear than those of the 75-mm. guns, since they are less mobile, more easily pinned to the ground by counter battery fire, and, if placed too far to the front, are an easier target for a hostile balloon to spot. Roughly speaking, in an at- tack, their positions may be expected to be found in a belt 2000 to 3000 yards from the enemy’s front lines. Due to the advantages of curved fire, and the fact that the range of the 155-mm. howitzer is longer than that of the 75-mm. gun, the tactical dispositions of the howitzer battalions do not offer quite as great variations as are to be met in the 75-mm. regiments. (j) When the number of battalion positions is lim- ited, since the forward displacement of the 75s is a very important matter in the attack, it may be expected that they will be allotted to the forward locations and the 155s emplaced rather more toward the rear. Bearing these fea- tures in mind, it may happen that the locations for the less mobile medium howitzers may be reserved for them by the artillery brigade commander and the regimental comman- der of a light regiment, in consequence, will be restricted as to the possibilities of tactical dispositions for his bat- talions. (k) A defensive position demands, as a rule, some dis- persion in depth. In such a case, the regiment usually is echeloned by battalion, one battalion in position behind the other ; or, the battalions may be placed in line with the bat- teries of the battalions disposed, with respect to each other, so as to give the depth desired. 6. Sectors of Fire. — (a) A reference to the plan of the dispositions of the artillery battalions, shown in the last sketch, will indicate how the sectors of fire are important. It is the duty of the regimental commander, in the attack and defense, to insure the covering of the front assigned; XI— 6-9 180 TACTICS AND TECHNIQUE— ARTILLERY also, he must consider the support of adjacent units in emer- gency. His battalions should be so disposed as to give the greatest sector of fire possible to obtain, consonant with other conditions. (b) When time permits, a very important study to be made is that of dead spaces formed in the sectors of light regiments, with a view to reporting them to artillery bri- gade headquarters, in order to insure their being covered by the curved fire of the howitzers. 7. Troops to be Supported. — This arrangement is made by the artillery regimental commander with the commander of the unit to be supported. The division order probably will be brief and direct; for instance, “The 1st FA will support the 1st Brig from the vicinity of Two Taverns. ,, How this support will be given, will depend on the division plan and how the infantry brigade commander intends to apply his force locally. This all should be thoroughly un- derstood by the artillery regimental commander,, if possible, before he is obliged to select localities for his battalions. 8. Enemy Batteries. — (a) These are to be neutral- ized or destroyed. Assignments of this kind frequently fall to the 155-mm. howitzers (which may be associated with the division) on account of their very accurate fire com- bined with their great crushing power, although 75-mm. units may receive such missions. (b) When several hostile batteries have been located, and assigned to the regiment as targets, it will be the duty of the artillery regimental commander to apportion them to his respective battalions and indicate also the sequence of attack. 9. Movements From Position to Position. — Since such movements are ordinarily made by battalion, when the situation permits, it becomes the duty of the regimental commander to supervise and direct such changes. Where there is plenty of time, in a thoroughly prepared assault, tables of displacement (sometimes by battery) will be de- veloped beforehand; in fact, the movements of the bat- talions may be taken up in detail by the artillery brigade commander, and the regimental commander will be called XI— 9-10 THE REGIMENT 181 upon to see that these displacements actually are effected at the time scheduled. 10. Regimental Headquarters. — (a) These duties are outlined under “Functions” as given in the Type Or- ganization sheets issued by these Schools. More should be said in regard to the Plans and Training section. (b) In action, this section will be very busy. In addi- tion to the field orders that it prepares, it must maintain, for the use of the regimental commander, a situation map that is based on the constant reports that are received, through the intelligence officer and liaison officers in par- ticular, and actually is kept up to the minute. (c) Frequently it will be engaged in duties that re- quire quite accurate drafting. When the artillery brigade commander sends a tracing, showing a barrage that is to be fired, he frequently transmits only the regimental task (though for coordination the brigade task may be indicated also). This must be divided between the battalions and a sketch of their particular tasks be sent to each of them. The Plans and Training section does this under the gen- eral instructions of the colonel or executive. It is the same for the parcelling out of successive concentrations that may be ordered. (d) When full latitude is left the artillery regimental commander, in the preparation of barrages and concentra- tions of a local nature, this section is very busily involved in details. (e) It must not be assumed that the Plans and Train- ing section, in the attack, has finished its duties when it prepares the details of the fire support necessary for the advance. The possibility of local stoppages of our infan- try must be provided for, and a study must be made as to where these embarrassing situations are liable to occur; the study of these possible emergency situations is of the greatest importance. (f) When opportunities allow, battalion commanders, in action, send frequent reports to regimental headquarters as to their firing and its effect, and frequently, a report when each battery commences and completes its mission. This allows the regimental commander at all times to know XI— 10-13 182 TACTICS AND TECHNIQUE— ARTILLERY how many batteries there are in action. He usually will have battery as well as battalion positions entered on the situation map, and, while firing, each battery so doing may be represented, say, by a red pin; the instant it becomes silent, on the completion of its mission, it will be indicated, maybe, by a blue pin. At a glance the regimental comman- der can see what batteries, if any, are available for an emergency call or to meet “eventual” duty. 11. The Service Battery. — (a) Tactically, it should be observed that this organization automatically can take care of those situations in which single battalions are de- tached, the appropriate sections of the service battery ac- companying the detached battalion. (b) When the regiment is operating as part of a divi- sion in active service, the battery always remains under the administrative control of the regimental commander, but works very closely with the G4 office of the division, and receives instructions therefrom, direct, in matters relating to the drawing of supplies, certain movements associated therewith, and some other similar matters. (c) It is thus seen that the service battery must oper- ate, to a great extent, some distance in rear of the battle positions of the troops. 12. Reconnaissance. — Frequently the position to be occupied by a regiment is very narrowly circumscribed. The regimental commander habitually should go over the terrain and assure himself, by actual reconnaissance, of the most suitable locations for his battalions within the limits imposed. He selects the general locations of his battalions, to carry out known or anticipated missions, and leaves the more detailed reconnaissance to his battalion commanders. For a more detailed discussion of reconnaissance, see Chap- ter VI. 13. Communications. — The normal procedure is for the regiment to establish communication with its battalions, but frequently the reverse is more expedient and may be so ordered by the regimental commander. When a regiment can establish an axis of communications, the battalions may be required to run a telephone line to the nearest switch- XI — 13-15 THE REGIMENT 183 board on this axis. For a detailed discussion of communica- tions see Chapter VII. 14. Observation. — In combat, one or more organized observation posts may be essential to the regimental com- mander both for intelligence and command. The habitual use of the battalion observation posts, by the regimental commander or his staff, is strongly condemned, since it puts an unnecessary burden on the battalion lines of communica- tion, crowds the space needed by battalion headquarters, hampers the battalion commander, and places the burden of upkeep, and repair, as a rule, on the battalion with inci- dent ill feeling in consequence. The regimental intelligence service, in so far as terrestrial observation is concerned, depends largely upon the battalion observation posts. 15. Regimental Orders. — (a) These are generally in the written five-paragraph form, with tables, diagrams and maps enunciating in detail the plan of fire action and scheme of maneuver for the regiment as a whole, and for each bat- talion thereof. (b) The five paragraphs of the artillery regimental order include all or part of the following, as the situation demands: (See “Combat Orders”) Par. 1 . — Information of the enemy and of our supporting troops. Zones of action by description or reference to an at- tached map or tracing. Location and missions of artillery units with which cooperation is necessary. Par. 2 . — General plan for the employment of the regiment. Par. 3 . — Instructions to the different battalions of the regi- ment — a separate lettered subparagraph to each battalion giving positions to be occupied, routes of advance to the initial posi- tions when necessary, unit or sector to be supported, other tac- tical instructions. In case a new groupment is organized, give its composition and commander. Much of this information may be shown by attached maps or tracings. Subparagraph (x) contains instructions applicable to all units of the regiment, such as the details of the artillery prepara- tion and accompanying fire in case of attack; and, in case of de- fense, the details of counter preparations and other defensive fires, and the conditions under which they are to be delivered. Instructions as to the kind and quantity of ammunition to be used, especially the employment of special shell, instructions regarding the assignment of accompanying batteries and accom- panying guns, advance of artillery in case of attack or retirement in defense, time to be ready to fire, and restrictions as to hours of firing. Par. U . — Designation of collecting station and ammunition distributing point. When necessary, instructions relative to the field and combat trains and regimental service battery. XI— 15-17 184 TACTICS AND TECHNIQUE— ARTILLERY Par. 5 . — Plan of signal communications. Axis of signal communications: That of the regiment, and of such other units as may be necessary. Command posts: of the regiment, of the battalions and of other artillery and infantry units with which the regiment is directly concerned. (c) In moving situations, the regimental orders are generally dictated or verbal, and often very fragmentary. They are supplemented whenever possible with tables, dia- grams, and marked maps or tracings. Section II The Artillery Brigade Paragraphs Composition 16 Headquarters of a Field Artillery Brigade 17 General Functions 18 Tactical Employment of the Brigade 19 Sectors of Fire 20 Regimental Principles Applicable to Brigade 21 Summary of Battle Functions 22 16. Composition. — This is discussed in Chapter I; for further details see Tables of Organization. 17. Headquarters of a Field Artillery Brigade. — (a) This is outlined in the Tables of Organization; for a study of the arrangements for its interior operation, see list of the functions of each section as set forth in the table is- sued by these Schools showing the “Type Organization/’ (b) This unit is partially motorized. Riding horses are provided for mounted reconnaissance, messenger ser- vice and telephone details. (c) The Intelligence Section, and the Plans and Train- ing Section, ordinarily will require a great deal of drafting to be done under certain battle conditions, hence the detail of specially trained warrant officers in these sections to per- form this duty, some of which requires very accurate execu- tion. XI— 17-18 THE ARTILLERY BRIGADE 185 (d) The enlisted detachment is organized very much like that of artillery regimental headquarters, discussed in a previous paragraph. 18. General Functions. — (a) The artillery brigade is a tactical unit. In the division, its commander is at the head of an organic group assigned as the artillery of the division. He is responsible for the training, fighting effi- ciency, and morale of this group, and, at the same time, is the artillery advisor of the division commander. He is, therefore, both a commander of troops and a staff officer of the division, hence his staff and headquarters must be or- ganized to assist him in both capacities. His staff depart- ments must function in close association with the corres- ponding staff sections and services of division headquarters. (b) The brigade headquarters should be the guiding element in the artillery command. It should be so organ- ized and trained that it functions automatically, giving the brigade commander frequent opportunities to leave his com- mand post and division headquarters to visit his regiments, individual batteries and observation posts, keeping in close touch with the situation in front and the performance of his units, as well as in touch with division headquarters. (c) In addition to controlling the policy and perfor- mance of the artillery within the division, brigade head- quarters must keep in close touch with supporting corps and army artillery units, with the artillery of adjacent divi- sions, and with the corps artillery information service. (d) Through the brigade munitions officer it controls and is responsible, in coordination with G4 of the division, for supply of artillery ammunition. (e) The brigade commander, through his communica- tions officers, must exercise a strict control over artillery signal communications, especially the artillery telephone net, to prevent the waste of equipment and duplication of energy that would result were subordinate units to put in too many independent lines. Normally the brigade lays the telephone lines for communication with the regiments, but, in many cases, the brigade will establish an axial line, and require the regiments to lay lines to the nearest brigade switchboard. XI— 18 186 TACTICS AND TECHNIQUE— ARTILLERY (f) The brigade commander controls the disposition of his regiments to carry out the plan of action in accor- dance with the orders of the division commander. He may indicate on the map, to the regimental commanders, merely the general area to be occupied by the regiment and the general dispositions of the battalions or batteries thereof, relying upon the regimental commanders to make a de- tailed reconnaissance of the areas assigned; but, whenever possible, the brigade commander should go over the ground himself so as to have a full appreciation of the suitability of the terrain for artillery positions. (g) He exercises supervision over the connection with infantry units, and the support thereof by the artillery units of his brigade, especially when mutual support must be pro- vided for between one sector and another. (h) As stabilization develops, he establishes the policy for the organization of battalion observation posts so as to distribute them over as wide a front as possible. When observation is limited, and but few points are available to the division artillery as observation posts, the brigade com- mander makes an allotment of these locations. (i) Field Orders . — (1) The field orders issued by the artillery brigade com- mander to his command are more often written than verbal. In combat, the initial order is supplemented by other written or verbal orders made necessary by unforeseen developments of the engagement. (2) The brigade commander and his Plans and Training Section assist the division staff in preparing such parts of a divi- sion field order as relate to artillery employment. The Plans and Training Section depends on the Intelligence Section for a great deal of information, much of which may be plotted and will include locations of hostile batteries, enemy works, movements within the enemy lines and much similar information. The plan of action of the division being understood, the tasks are appor- tioned to the various regiments and battalions through the Plans and Training Section. This often requires accurate drafting. When barrages are used, the regimental tasks are transmitted by sketches showing the time each part is to be laid. A similar system is used for concentrations. (3) When an artillery annex is needed within a division field order, to give more details of the artillery employment, the ar- tillery brigade field order is used as this annex (see “Combat Orders ”) . (4) (a) The following extract from Instruction Memoran- dum No. 1, Sept. 15, 1920, General Service Schools, should receive careful consideration in connection with plans and orders for artillery, as setting forth the school policy with respect to same. XI— 18 THE ARTILLERY BRIGADE 187 Plans of action for tactical commands versus separate plans for each combat arm: Separate plans of action for each combat arm (infantry-artillery-tactical air service, etc.) have no place in the organization (especially in open war- fare situations) and in considerations of higher comman- ders. The plan should be based on tactical units and the arms comprised therein employed in combination. One of the most dangerous procedures developed in the stabilized warfare of the western front was the formulation of separate plans of action for each combat arm. In study- ing some of the important battles which occurred between 1915 and 1918, and especially the plans of action of division commanders, it is found that they frequently comprised an infantry plan — an artillery plan — an air service plan, etc. These various plans were published by the commanders of each separate arm and showed a lack of the proper employ- ment of the combined arms. The organization of the divi- sion into separate infantry and artillery commands and long periods of inactivity prompted this procedure. The scheme indicated in the foregoing is most injurious to sound tactics as it tends to an independent and uncoordi- nated employment of the infantry, artillery, tactical air ser- vice, etc. From the viewpoint of the division commander, such a thing as a separate infantry plan and a separate ar- tillery plan should never enter into his consideration. He should frame a divisional plan which combines all arms in a predetermined scheme of maneuver. While this scheme of maneuver is based primarily on the infantry action there should be no separate infantry plan. Likewise, subordinate infantry commanders should not limit their considerations solely to a purely infantry plan. Aside! from machine guns, tanks, and other special infantry weapons, the infantry commander must make certain of use- ful assistance by his supporting artillery. At the same time, commanders of divisional artillery units should include in their considerations and plans the action contemplated by the infantry units they are to support. While each commander must necessarily evolve a plan for the employment of his command, and consider therein the part to be played by all units of his command, and those associated therewith, his final and accepted plan is issued in the form of field orders and not as a plan. Therefore, the policy of the Schools does not recognize the formation and issuance of plans by separate arms of service as “infantry plans, artillery plans, tactical air service plans, etc.” The policy is that the commander of each tactical unit (whether it comprises all arms or only one) must, after formulating a plan of action to carry out the mission assigned by higher authority, announce the accepted plan in the form of field orders. Therefore, instead of infantry plans, artillery plans, etc., there should be army, corps, division, brigade, regi- ments, battalions and detachment field orders (see Combat Orders ). There must be divorced from all minds any thoughts of “going it alone” by the infantry or the artillery, and there must be uppermost in all minds that all plans and field orders are based on the plans of the commanders and not of separate arms. The plans of these commanders should seek to secure proper combined employment of all the arms. XI— 18-19 188 TACTICS AND TECHNIQUE— ARTILLERY With the foregoing in view, chiefs of combat arms on the staffs of commanders have no tactical command of troops of their arms in lower units and do not give tactical orders thereto. All tactical orders are given to unit commanders and in accordance with the hierarchy of unit command and not of arm of the service. (b) However, there should be direct communication be- tween army, corps and division field artillery commanders; not for the purpose of transmitting orders, but to secure a closer cooperation of the three classes of artillery in carry- ing out existing orders. Artillery of one class frequently will call on artillery of another class to assist it in its mis- sion. This assistance frequently can be rendered without detriment to the accomplishment of its own normal mission. 19. Tactical Employment of the Brigade. — (a) It is the duty of the artillery brigade commander to determine the areas from which his regiments can accomplish their missions. In the selection of regimental areas, the two ex- tremes of congestion and over-extension are to be avoided. Congestion limits subordinates in their choice of battalion areas and battery positions. Over-extension adds to the difficulties of command, coordination and supply. The ar- tillery brigade commander’s versatility in the selection of regimental areas is measured by his ability to meet existing conditions by a skillful compromise between these two ex- tremes. (b) For the purpose of illustrating a few of the tacti- cal dispositions of the regiments of field artillery operating within a division, the following cases are presented. In each case, it is assumed that a regiment of medium howitzers is attached to the division. 1. Case 6. Open Warfare . — The 1st Field Artillery is sup- porting the 1st Brigade and the 2d Field Artillery is supporting the 2d Brigade. The 101st Field Artillery (medium howitzers) is held in general support of the division. Contact with the enemy has developed as indicated. See the sketch. It is not drawn to scale and is intended only to illustrate the principle. For obvious reasons, the area to be assigned the 1st Field Artillery should be more advanced than the 2d Field Artillery area. This leaves a gap between the two areas, and, if the terrain permits, allows the medium howitzer regiment to be placed in a central location. This permits it to cover the entire front of the division at long ranges. This also allows deep penetration of the infantry before forward displacement of the howitzers is required. Moreover, if a con- venient longitudinal road net exist, the howitzer regiment may se- cure its own route forward, unhampered by the rear elements of the light regiments. Such simple conditions as are indicated in Case 6 can- not always be found. XI— 19 THE ARTILLERY BRIGADE 189 Case -6 2. Case 7 . — (a) Since the light guns are more mobile and more easily concealed than the howitzers, it may frequently occur that the more favored positions will go to the heavier weapon and the 75s will be forced to take whatever may be left. (b) In this case, the general situation is similar to that presented in Case 6. Here, however, a high ridge affords con- venient howitzer shelter, and is favorably located with respect to roads. In such a case, it may be expected that the artillery brigade commander will recommend to the division comman- der a reservation of the positions indicated for the medium howitzers. This will require the light regiments to conform to the situation as represented. The 75s, in this case, still would have the protection afforded by the upper slopes of the ridge, if such positions were desirable. Direction of A d vance XI— 19 190 TACTICS AND TECHNIQUE— ARTILLERY Case 7 3. Case 8 . — (a) Sometimes the howitzer battalions may be ao assigned that one is associated with one 75-mm. regiment and on« with the other, leaving a third for emergencies and general sup- port. Since this last named howitzer battalion must give gen- eral service under all conditions, both for fire within the division sector and possibly for eventual missions in the area of adjacent divisions, it is probable that the best location will be reserved for it. X* XI— 19-20 THE ARTILLERY BRIGADE 191 (b) In a large attack, when batteries from the army and corps artillery are intermingled with those of the division artillery, reservations for the former should be made and in- dicated to the division commander. He then knows what area remains to him for the sole use of his organic artillery brigade. In such an attack, most of the division artillery will be moved into more advanced positions at some time prior to the assault. Timely advice as to specific reservation of areas for corps and army artillery is important. It saves useless work in making later changes in division artillery locations. (c) The figure is intended to illustrate the case just pre- sented. 20. Sectors of Fire. — (a) Dead spaces often are found in the sectors of fire assigned to 75-mm. regiments. When important areas are included in such dead spaces, missions XI— 20-22 192 TACTICS AND TECHNIQUE— ARTILLERY within those areas are assigned to the attached howitzers, if any. As the situation becomes more stabilized, this fea- ture is more minutely examined, and charts of areas of all dead spaces are calculated carefully so that the tactical dis- positions can be regulated accordingly. (b) When the situation permits, artillery regimental commanders determine and designate the sectors of fire for the normal supporting missions, reporting their deci- sions to the artillery brigade commander. Artillery regi- mental commanders confer directly with the commanders of the troops supported in regard to this subject. (c) Sectors of eventual fire for artillery regiments should be prescribed by the artillery brigade commander, who arranges for a scheme of lateral artillery support, all in furtherance of a complete coordination with the plan of action adopted by the division commander. 21. Regimental Principles Applicable to Brigade. — The general principles relating to the regiment are, in sub- stance, applicable to the brigade. Hence, they are not re- peated. 22. Summary of Principle Battle Functions of Unit Commanders Within the Brigade. — This chapter has been utilized to emphasize the fact that, within the field artillery brigade, there are important matters of interior tactics that must be solved in battle, and that these matters are intimately connected with the exterior or supporting tactics which has been discussed in Chapter VIII. Exclu- sive of the important matters of training, marching, com- munications, reconnaissance, ammunition supply, etc., which must be directed by the respective commanders concerned, there are certain battle functions of the unit commanders that are typical and serve better to define the sphere of artillery effort in action. They are as follows : Battery Commander: Fire technique and fire control. Battalion Commander: Fire direction; technical location of batteries to render effective fire support. Regimental Commander: Battalion locations; fire direction; tactics of fire support and movement. Administrative and technical assistance to battalions. Brigade Commander: Fire direction; tactics of fire support and movement; general locations of regiments; staff offi- cer for division commander. XII— 1 CHAPTER XII Artillery on the March and its Entry into Action Paragraphs Disposition on the March 1 Subdivisions of Artillery on the March 2 Artillery Headquarters on the March 3 Conduct of Marches 4 Rates of March 5 Distances 6 Reconnaissance on the March 7 Communications 8 Entry Into Action From the March 9 1. Disposition on the March. — (a) The order of march, in the presence of the enemy, is controlled by tacti- cal considerations. The artillery is so disposed in the col- umn or columns, with respect to other troops, as best to meet the anticipated needs. (b) (1) The artillery with the advance or rear guard is usually in the proportion of one battery of light artillery to each battal- ion of infantry, or, expressed in terms of larger units, one bat- talion of light artillery to each regiment of infantry. This pro- portion is subject to wide variation, and depends entirely upon tactical considerations. In a pursuit, or in a retreat, this pro- portion might be increased considerably, whereas, in an advance at night, it would be unusual to have any artillery with the ad- vance guard. (2) In a cavalry division, there is but one battalion of ar- tillery, hence the proportion of artillery with the advance guard usually would be less 1 than in the infantry division. (c) In order to expedite its entry into action, artillery generally is placed near the head of the main body, but it must be preceded by sufficient infantry (or cavalry) to pro- vide for its security. The distance to the leading element of the advance guard must be such that the artillery will not come under hostile artillery fire while still in column. For this reason, artillery in the advance guard usually is placed at or near the tail of the reserve. Artillery with the advance guard is under the direct orders of the advance guard commander. When march conditions cease, advance guard artillery automatically reverts to the control of the 193 XII— 1-2 194 TACTICS AND TECHNIQUE— ARTILLERY commander of the artillery unit from which it was detached, unless otherwise ordered. (d) When contact with the enemy is expected, columns are closed up and march on broad fronts, taking advantage of all parallel roads or routes across country that permit good lateral communication. In such a formation the sub- division of artillery generally is made so that artillery units are with the infantry (or cavalry) units that they habitually support. (e) Placing artillery and infantry in the same column is taxing upon both the artillery and upon the foot troops. This disposition should not be resorted to except in the pres- ence of the enemy. Marches of concentration, such as the march of one division to relieve another division in the line, should be so conducted as to enable both horse-drawn and motorized artillery to march independently of each other and of columns of foot troops. (f) Good marching requires careful preparation and strict discipline. In the division, the march of all units is conducted in accordance with a march order. When units march independently the march order usually contains a march table, prescribing the time of departure, route, rate of march, and destination of each marching unit. For a march in column or columns, in the presence of the enemy, the march order prescribes the order of march, and, when necessary to avoid confusion, the route of each unit to enter the column. The time of departure necessary to reach the column at the proper time is a responsibility of subordinate commanders. 2. Subdivision of Artillery on the March.— (a) The battalion is the principal marching unit. When a bri- gade or regiment is in column, the march is conducted as the march of so many successive battalions, over which bri- gade and regimental commanders exercise a certain amount of supervision. This supervision usually is limited to in- spections and to prescribing the time and length of halts, when not fixed by the orders of the higher commands. (b) Unless marching independently, or as part of an advance or rear guard, a battalion combat train seldom marches immediately in rear of the batteries. The road XII— 2-4 ARTILLERY ON MARCH— ENTRY INTO ACTION 195 space that would be occupied by the combat train is given to troops needed in action before a re-supply of ammunition to the firing batteries can be necessary. (c) On the march with other troops in the presence of the enemy, the artillery regimental service batteries, or the parts thereof attached to battalions or independent bat- teries, march with the field trains of the other troops. Grain for one day is carried on the horses, and frequently, addi- tional grain and some hay is carried on the artillery car- riages of both the firing batteries and combat trains. (d) Adequate provision must be made for gasoline and oil supply, as well as for minor repairs to motor vehicles, for all subdivisions of motorized units on the march. 3. Artillery Headquarters on the March. — In an advance, when contact with the enemy is expected, parts of the headquarters of the artillery brigade, regiments, bat- talions and batteries are pushed sufficiently forward in the column to enable the reconnaissance to be completed and communications established before the batteries arrive at their firing positions. As a general principle, artillery re- connaissance should be expedited so that it may not be necessary to halt artillery columns while waiting for a re- connaissance to be completed. Otherwise traffic congestion is almost bound to result. 4. Conduct of Marches. — (a) Artillery on the march requires strict discipline and close supervision. For this reason, non-commissioned officers ride where they can sup- ervise the march of the units they command; and officers must be distributed along the column. (b) It is difficult for moifnted troops or motor vehicles in a long column to maintain a uniform gait throughout. Even when the head of an artillery column is not dependent upon other troops and can maintain what may appear to be a uniform rate of march, rear elements will be continually changing gait or even halting at times unless the column is broken by frequent intervals. (c) There is no greater evidence of the training and discipline of artillery than its conduct on the march. In a well trained organization, vehicles keep well to the right of the road; mounted men seldom if ever ride to the left of XII— 4 196 TACTICS AND TECHNIQUE— ARTILLERY the left line of wheels ; when a carriage must be taken out of column for adjustment or repair, its driver notifies the driver of the carriage in rear and then moves his carriage well out to the right of the road. When a carriage is taken out of the column, the battery commander is notified at once. (d) As soon as the carriage is able to resume the march, it is placed in column wherever possible, and resumes its normal place in column only after the column has halted, and then only in case traffic is travelling in one direction. At halts, artillery pulls off well to the right of the road, and keeps the road clear to the left of the left line of wheels. (e) The time and length of halts must be known in order that full advantage may be taken to dismount the drivers, to rest and water the animals, and to make adjust- ments and repairs. (f) When marching with other troops, or in long col- umns, artillery must depend upon buckets for watering ani- mals at the halts. Before the prescribed halts, canvas water buckets are made ready, and as many animals as possible watered at each halt when water is obtainable within a rea- sonable distance. (g) Short columns of artillery, such as a battalion, marching independently, may take advantage of watering places. Either the entire column may halt for water, or if watering places are small, platoons or batteries are dropped out of the column from the rear at each successive watering place. After watering the animals, each platoon or battery will continue the march without increasing the gait, and usually will catch up to the element ahead about the time the latter completes watering. In this way the column is quickly reformed. (h) (1) The principles for conducting the march of motorized artillery are essentially the same as those for horse-drawn or- ganizations. However, it is much more difficult for motorized artillery to march in the same column with foot troops. It is far preferable to place motorized artillery in the interval be- tween the main body and the field trains, or on a parallel road so that it can move forward by successive bounds. (2) It is difficult for a regiment of motorized artillery to march (even by itself) as a unit. Tractors, trucks, automo- biles and motorcycles, all have different speeds and cannot be XII— 4-7 ARTILLERY ON MARCH— ENTRY INTO ACTION 197 moved readily together. If possible, a truck column should march separately, and automobile and motorcycles with the trac- tor column be towed or allowed to move by bounds. 5. Rates of March. — (a) When marching in a mixed column, the rate of march of artillery is governed by that of the troops with which it is marching. For light artil- lery marching independently, the rates of march are given in the organization tables issued at the General Service Schools. These rates include halts, and must be taken merely as a general guide: Good roads: 31 miles per hour. Mediocre roads: 3 miles per hour. Poor roads: 21 miles per hour. Motorized artillery of medium caliber may be assumed to march at the same rate as horse-drawn units. Of course the above rates can be considerably increased, particularly in the case of small units. They are given as average rates for marches of one or more days. (b) The rates for marching and maneuvering off the roads vary so greatly with the terrain that estimates would be futile. The maneuvering gait for light artillery is the trot. In training, animal-drawn artillery is gaited as fol- lows: Walk 4 miles per hour. Trot 8 miles per hour. Gallop 12 miles per hour. 6. Distances. — (a) The distance that motorized ar- tillery may march is limited only by the rate of march pos- sible and the marching time available. For horse-drawn ar- tillery, the distance is affected by the condition of the ani- mals, the weather, the condition of the roads, and the num- ber of successive days that a march must be continued. Mo- torized artillery may halt anywhere, whereas horse-drawn artillery must bivouac near water, and, if possible, where horses can be sheltered, and grazed. (b) Portee artillery has a much greater daily march- ing radius, when suitable roads are available, than has trac- tor-drawn artillery. For that reason, it is assigned to the G.H.Q. artillery. 7. Reconnaissance on the March. — (a) The com- mander of the artillery with the advance guard must be XII— 7 198 TACTICS AND TECHNIQUE— ARTILLERY with the advance guard commander, whenever contact with the enemy is expected. This usually will place him well ahead of his guns. He, as well as all other artillery officers, must study the ground and the map as the march pro- gresses. He must know the ground he has passed over for considerable distances on both sides of the road, the way this ground lends itself to artillery employment, and all routes to possible positions. In selecting routes, the im- portance of covered approach must be remembered, also the advantage, where possible, of using a road that will be free of other troops. His formal reconnaissance commences as soon as he has received instructions from the advance guard commander as to the desired employment and loca- tion of his guns. If he is a battalion commander, he must take with him on his reconnaissance either the battery com- manders, the battery reconnaissance officers, or the battery agents. (b) The reconnaissance by artillery units attached to infantry brigades, regiments, or battalions, is conducted in a similar manner. (c) (1) Reconnaissance by division artillery is progressive, as it is with smaller units, and commences, when possible, with the brigade commander. He may make a partial reconnaissance on the ground, or merely a map reconnaissance, and send instruc- tions to his regimental commanders by messages. He may as- semble his regimental commanders for reconnaissance, or he may start his reconnaissance without delay, sending word to his regimental commanders to meet him at a designated rendezvous point. (2) Whatever may be the method of his reconnaissance, its object is to indicate to the regimental commanders the general disposition of the brigade with respect to the terrain and with respect to the other units of the division. (3) Regimental commanders select general locations for their battalions, leaving to the battalion commanders as much latitude as possible in the actual selection of the battery posi- tions. (d) Prior to making a reconnaissance artillery * com- manders must have as complete a knowledge as possible of the plan of artillery employment desired by the superior command. (e) For a more detailed discussion of artillery recon- naissance see Chapter VI. XII— 8-9 ARTILLERY ON MARCH— ENTRY INTO ACTION 199 8. Communications. — (a) On the march, and prior to actual contact with and resistance by the enemy, communi- cation is maintained by motorcycle and mounted couriers. When necessary, the employment of radio may be resorted to; and, very exceptionally, visual signal stations. When available, the commercial telephone system is utilized. (b) After contact has been gained with the enemy, the establishment of telephone communication, and the building up of an artillery telephone net commences simul- taneously with the reconnaissance. Radio communication is established as soon as the command posts of battalions, regiments and the brigade are selected. See also Chapter VII. 9. Entry Into Action From the March. — (a) When the march forward is stopped by sufficient hostile resistance to require the employment of artillery, the efficiency of the artillery is gauged by the promptness with which it is able to deliver an effective fire. This requires a rapid reconnais- sance, and an almost immediate occupation of positions by the artillery with the advance guard. The advance guard commander decides when the artillery shall open fire. When fire is desired, it is the duty of artillery to be able to deliver it at once, and to deliver it effectively. (b) At least one battery should be placed in position not far from its location when the column is stopped, pro- vided, of course, it is able to deliver an effective fire from such a position. Even though the range may be somewhat longer than desired, the prompt opening of fire by our ar- tillery has a considerable moral effect upon the infantry, and tends to inspire confidence. There will be cases, how- ever, when, due to lack of nearby observation facilities, con- siderable time necessarily will be consumed in establishing observation posts and lines of communication. Part of this time may be used in pushing the battery to a more ad- vanced position instead of having it quickly occupy a nearer position with a resultant period of idleness. Having estab- lished fire with one battery, others may be moved further forward, under cover of its fire, into positions selected after a more thorough reconnaissance. When these advanced XII— 9 200 TACTICS AND TECHNIQUE— ARTILLERY batteries have opened fire, the first battery in action then may be moved to a more suitable position. (c) In meeting engagements, artillery officers must realize that time is the important element ; that moving bat- teries over considerable distances across country, or along roads congested by other troops, involves delays; and that it is better to open fire from inferior positions, and open fire promptly, than to hold batteries inactive during a long and exhaustive reconnaissance. (d) If the enemy resistance is considerable, and espe- cially if the hostile artillery has a superiority of fire over the artillery of the advance guard, the artillery with the main body cannot be too prompt in going to its support. Such a condition may require the leading elements of the artillery with the main body to take up positions near their location in the column at the time the column is halted. Such positions usually will require very long ranges, and must be considered merely temporary positions, employed to sup- port the advance guard artillery, and to support the advance of the other batteries with the main body into more favor- able positions well to the front. (e) These rear positions may serve another useful purpose. In case of a reverse, or in case it is necessary to withdraw the advance guard to a position in rear of that which it originally occupied, the fire from these rear posi- tions will aid the withdrawal, and may save the command from a serious defeat. Therefore, until the strength of the enemy is sufficiently determined, artillery must be well echeloned to the rear. As soon as a superiority of fire is definitely established, the artillery is closed up toward the front, for it must be remembered that, with certain limita- tions, the effectiveness of artillery fire is inversely propor- tional to the range. (f) To summarize: In its entry into action from the march, the positions occupied by and the employment of the artillery depend upon the plan of attack or defense decided upon by the commander of troops. The entry into action is usually progressive, but with a minimum delay once the plan of action is definitely determined. The prompt estab- lishment of a superiority of fire is an important considera- XII— 9 ARTILLERY ON MARCH— ENTRY INTO ACTION 201 tion. If the action is to be aggressive, as many batteries as possible should be pushed forward to good positions prior to the deployment, and support by a superiority of fire, the deployment of the infantry, its advance and fire attack to a line of departure, the assault against the hostile positions, and subsequent phases of the engagement. The latter generally requires a forward displacement of the ar- tillery and sometimes the assignment of accompanying bat- teries. For defense, the artillery is generally disposed in greater depth. (g) In a retreat, batteries hold positions as long as it is expedient to do so, and frequently may be sacrificed for the purpose of holding the enemy as long as possible at im- portant points. Batteries or battalions withdraw succes- sively under cover of the fire of other batteries or battalions occupying positions further in rear, and, in their turn, occu- py positions to support the withdrawal of other artillery units, and, at the same time, to assist the troops of other arms in checking the enemy. The long range of artillery may be made extremely useful, in retreat, by forcing hostile deployment at great distances, thus delaying pursuit. XIII— 1 CHAPTER XIII Accompanying Batteries and Accompanying Guns Defined General Purpose Historical When Used Duration of Mission, Orders Command of Accompanying Artillery Missions Handling and Maneuver of Accompanying Artillery Units From Which Accompanying Artillery Should be Detailed Moral Effect of Attached Artillery Attached Artillery Drawing Fire Equipment of Accompanying Artillery Suitability of 75-mm. Gun Necessity for Combined Training Paragraphs 1 2 3 4 6 7 8 9 10 11 12 13 14 1. Defined. — (a) The artillery employed for infantry support is of two categories, depending on its system of command and method of functioning tactically, i.e., sup- porting artillery and attached artillery. Accompanying batteries and accompanying guns are forms of attached ar- tillery especially used in connection with an attack against a defensive zone and in other situations in which the at- tack involves continuous fighting over a considerable depth and in which the supporting artillery alone would not yield the maximum effectiveness. Accompanying batteries are batteries attached to subordinate infantry units, ordinarily the brigade or regiment. Accompanying guns are single pieces attached ordinarily to infantry assault battalions. Thus they are distinct from the mass of supporting artillery usually present in such situations. Accompanying artillery refers to accompanying batteries and accompanying guns only. (b) While accompanying batteries and accompanying guns are forms of attached artillery, it by no means follows that all attached artillery is either accompanying batteries 202 XIII— 1-3 ACCOMPANYING BATTERIES— GUNS 203 or accompanying guns. For example, artillery may be at- tached to infantry commands in advance and rear guards, pursuits, retreats, in defensive situations, and even in at- tacks. In such cases, the terms accompanying batteries and accompanying guns would not be applicable, strictly speak- ing, although the methods of the latter might be appropriate with little modification. The term “accompanying gun” is not applicable to the infantry auxiliary weapons, such as the light trench mortar and the 37-mm. gun. 2. General Purpose. — It is a well recognized fact that, no matter how powerful the general artillery and other fire support in attack may be, some elements of the hostile resistance, particularly automatic weapons, will re- main in action to a certain extent and will be encountered by the advancing infantry. Advance provision for attack- ing these targets cannot be made, except in a general way,, since their location is not known beforehand. When they actually are encountered, it frequently is possible for the in- fantry to overcome them with rifle fire and movement alone, but usually this procedure results in undue losses, and is productive of delay. Again, it may be possible to employ suc- cessfully the special infantry weapons, the machine gun, the light mortar, and the 37-mm. guns; but on the other hand, these may prove to be inadequate in power. In this latter case, recourse may be had to the supporting artillery ; but this expedient may prove unsatisfactory, due to long and faulty communications, lack of observation, difficulties of target designation at a distance, and inaccuracy of long range fire. In general, the problem of meeting these unex- pected resistances is to bring into play a fire action of suf- ficient power in a minimum of time, in order to save the in- fantry time and losses. To augment the power of the spe- cial infantry weapons and to reduce the delay and inaccur- acy of the fire response of the supporting artillery, accom- panying batteries and accompanying guns were introduced. 3. Historical. — (a) Accompanying guns appear to have been the earliest form of mobile artillery, and their use, as such, is historically recorded as early as nearly four hundred years ago. The historical references which fol- low relate to The World War. XIII— 3 204 TACTICS AND TECHNIQUE— ARTILLERY (b) The Germans made more extensive use of accom- panying batteries and accompanying guns than did the al- lied armies. In some cases, the guns were taken from the division light artillery. In others, the guns were formed in independent batteries ; the latter were armed with materiel of various types, such as the 77-mm. gun on low wheels, the 76-mm. Russian gun, the 75-mm. and the 77-mm. mountain guns, and 57-mm. naval guns. A captured document of about September 1, 1918, states that the guns “must en- gage at short range the enemy with whom the infantry is fighting at close quarters. By reason of their proximity to the infantry, they can be fired at the right moment and on the right target more easily than the artillery in the rear. Also, being at close range, they can fire on objectives which cannot be observed from the rear.” (c) The British conception is similar. To quote from an official document : “The fighting throughout August and September (1918) has confirmed previous experience regarding the vital necessity for closely supporting the advance of the leading infantry with field guns Sections (platoons) of 18-pounder batteries, rather than single guns, should be allotted to assaulting battalions.” (d) In our operations, accompanying guns were used first in the St. Mihiel operations, in obedience to instructions from the Commander-in-Chief, but to a negligible extent; their use was more extensive in the Meuse-Argonne opera- tions. The experiences varied greatly, the greater part of the cases resulting in failure to accomplish the mission, and with occasional losses of personnel, animals and materiel. As a result, extensive opposition to the use of such guns developed, based on various contentions ; and the discussion was out of all proportion to the relative importance of the guns in the general artillery scheme. A study of our ex- perience however shows the following : (1) In all but a few cases, both the young artillery officers commanding the guns, and the infantry commanders with whom they worked, had little or no training in the use of such guns, and knew little of the purpose or tactics. (2) They were used in situations wftich were not appropriate. (3) In many cases, they were mishandled to such an extent, due to both the artillery and the infantry, that failure was almost a foregone conclusion. XIII— 3 ACCOMPANYING BATTERIES— GUNS 205 (e) A mere tabulation of successes and failures is, therefore, no criterion of the value of such guns when pro- perly employed. The Chief of Artillery, 1st Army, A.E.F., stated: “There have been repeated instances on the pres- ent front of their effective use ; of their abuse and of their neglect. ,, Under date of December 11, 1918, the Inspector General, A.E.F., reported in part as follows: “According to the energy of the artillery officer handling the accom- panying guns, the experience under fire of the infantry bat- talion commander, the liaison between the two, and the ter- rain, they were used with varying successes. In one divi- sion (the 82d) one accompanying gun with the assault bat- talion destroyed eight pill boxes in one day which at vari- ous times held up the infantry advance.” Later in the same report: “ — th Division: In the — th Infantry Brigade, one platoon of Battery A, — th Field Artillery, was assigned as the accompanying guns to one of the assaulting battalions of this brigade. The guns went forward during the night 31 Oct.-l Nov., 1918. Twelve horses were killed by shell fire and machine guns. This platoon was relieved 2 Nov. 1918, having accomplished nothing. Those with the — th Infantry fell back behind the assault battalion but fired about 175 rounds against machine gun nests with good effect.” A staff officer who witnessed the action of this same di ision on November 2, 1918, reported: “We encoun- tered an infantry company commander whose company was held up before the village 0 f * * * * According to his statements, he was using all the fire power at his disposal to overcome a very strong machine gun resistance but seemed doubtful as to whether he could make a go of it. We asked him why he did not call for artillery support. He re- plied that he was trying to get artillery support but could not get communication, although he thought it might come later. We passed through artillery brigade headquarters several hours later and General * * * * * then mentioned that the infantry was calling for artillery fire near (same village).” This village could have been attacked by artil- lery at short range with perfect observation, and with the position and its approaches completely under cover ; the ar- tillery was not there however, but was considerably to the rear and out of communication. XIII— 4 206 TACTICS AND TECHNIQUE— ARTILLERY 4. When Used. — (a) In deciding to use batteries or guns attached to infantry, it must be remembered that their detachment from the mass of supporting artillery weakens the latter. They are removed from that organization of command and supply which, in the general case, is designed to employ the artillery with greatest effectiveness; an or- ganization with which they are perhaps best trained and most accustomed to Work and with which they receive the supervision and assistance of more experienced artillery commanders. (b) The use of accompanying artillery is justified only in prevision of a probable failure of the supporting artil- lery in some later phase of the action. Such failures more often ensue when the penetration into the hostile lines is rapid and deep. These failures may be due to any of the following causes : loss of mobility on account of casualties, poor roads or traffic congestion; loss of observation; inef- fectiveness of long range fire ; severance of communications ; etc. Unless such failure is foreseen with reasonable certain- ty, accompanying artillery is not used. It follows, there- fore, that supporting artillery is the rule, accompanying artillery the exception. The ratio of accompanying artil- lery to supporting artillery usually is small. (c) In the case of an attack against a single prepared position, it may be expected that the artillery positions are well forward with ranges short. Observation is organized, communications are established, firing data are prepared for a large number of points, some adjustment of fire doubtless has been made, artillery liaison officers are with infantry commanders; there is therefore no reason to ap- prehend delay or ineffective fire, in response to calls for artillery fire, even on unexpected resistances. Hence, the supporting artillery, in general, should be kept intact. (d) In an attack against a defensive zone of two or more prepared positions, the first position presents the same aspects as a single prepared position. As far as this posi- tion is concerned, the integrity of the supporting artillery ordinarily should be maintained. Conditions are different for the second position. It must be expected that the at- tacking infantry will have lost their formations to a cer- XIII— 4 ACCOMPANYING BATTERIES— GUNS 207 tain extent when they arrive at this position; the position will be out of effective range of the initial artillery positions, and the artillery in general must advance shortly after the first position is captured; observation will be possible, but will not be organized, communications will be established hurriedly and imperfectly ; a certain portion of the artillery may not have arrived yet at the new positions. For the sec- ond position, the attack will have lost some of its cohesion and crushing power, and the supporting artillery will be less effective; yet the attack has acquired momentum and must be pushed without allowing the enemy time to reor- ganize. Moreover, between the first and second positions, the enemy will have isolated strong points, centers of resis- tance, intermediate and switch positions, and other organ- ized areas, which will tend to slow up the attack and disor- ganize it. Many of these points cannot be known before- hand. It is to be expected, then, that the infantry will feel the need of artillery constantly close at hand when they at- tack the second position; and probably not long after they pass the first position, depending on conditions. How much artillery thus is needed will depend still more on conditions. The second position ordinarily will require fairly complete artillery support, and strong endeavor will be made to have the supporting artillery available at this time. In case little resistance is anticipated at the second position, and the artil- lery is likely to be delayed in crossing the first position, it might be advisable to employ accompanying batteries at the rate of one battery per infantry regiment in front line, or one light battalion per infantry brigade in line. Accom- panying guns might be taken from this quota if desirable. An infantry brigade commander having more than one ac- companying battery is at liberty to pass them on to his regi- ments. (e) For the attack of the third position or after pass- ing the last organized hostile position, the conditions which make attached artillery advisable before attacking the sec- ond position obtain to a still greater extent. The supporting artillery may keep up with the infantry with difficulty ; some, particularly the medium and heavy artillery, may lag be- hind; the attack develops into a series of local combats, XIII— 4-5 208 TACTICS AND TECHNIQUE— ARTILLERY more or less detached; and the infantry commander con- cerned must handle them on his own initiative and be re- sponsible for results. Such cases call for accompanying bat- teries, used as such or as accompanying guns. (f) In general, there is no fixed practice in the use of accompanying artillery ; its proper employment is a phase of the artful handling of artillery. While the foregoing dis- cussion of the attack against a defensive zone illustrates situations which might call for accompanying batteries and accompanying guns, their use is not restricted to this parti- cular case. The same necessities could arise in situations where the elements of a defensive zone are lacking; these necessities may be local or general ; they may be incident to open operations as well as a stabilized situation. The use of accompanying artillery in appropriate cases is to be encour- aged. But as stated previously, the practice is an exception to the usual procedure of supporting artillery, and should be justified by conditions as they exist or as they can be fore- seen. 5. Duration of Mission of Attached Artillery. — Orders . — (a) There were cases in France in which accom- panying guns, assigned initially for a particular operation, remained absent from their batteries for several days, during which time the operations and the situation changed completely, and the guns were idle most of the period. This is faulty procedure. Since the use of accom- panying artillery is exceptional for special situations, such pieces should revert to their proper organizations imme- diately on completion of the missions contemplated, or when they no longer are useful. Orders should be as explicit as possible as to the period of attachment ; but if the orders are indefinite in this respect, the commanders immediately concerned should initiate measures to return the artillery when it is no longer useful. Ammunition and other supplies are obtained with difficulty by detached and scattered artil- lery units. (b) Accompanying artillery might well be used for a particular day only, on the assumption that, during the suc- ceeding night, the supporting artillery can be advanced so as to make it unnecessary thereafter. Or the orders might XIII— 5-6 ACCOMPANYING BATTERIES— GUNS 209 call for such batteries or guns during a particular phase of the operation, as after the capture of such a position, etc. (c) Situations might arise during an operation in which a supporting artillery commander would employ some of his artillery in the manner of accompanying batteries or accompanying guns, though the technical formalities of or- ders and commands would be lacking. Such a case would be the sending of a platoon or piece to take a particularly favorable position for a certain mission, as, for example, firing on a moving hostile column ; the platoon to return on completion of the mission. (d) In an attack from stabilization, it usually is neces- sary to detail accompanying guns, if used, before the at- tack on the first position, though their use is not contem- plated until later. Otherwise there may be difficulty in overtaking and finding the infantry unit to which a gun is attached, after this unit has advanced a considerable dis- tance. In such a case, the guns usually do not participate in the initial preparation and general fire support for the attack of the first position. This advance detachment would be less necessary in the case of accompanying batteries, for, as a rule, they are not needed as early in the attack. (e) It is advantageous to indicate the assignment of accompanying artillery at the earliest moment practicable in order to secure the opportunity for the artillery comman- der to conduct visual reconnaissance, to estimate his tasks, to make any preparations to overcome engineering difficul- ties, or to compute firing data when it appears that the guns may be used from their initial position. This gives the in- fantry commander also an opportunity to fit the accompany- ing artillery into his local plans. 6. Command of Accompanying Artillery. — (a) Ac- companying batteries and accompanying guns, for the time being, are detached completely from their artillery com- mand, and are exclusively under the commander of the in- fantry unit to which they are attached. Faulty exercise of this command, usually through lack of understanding of the employment of such artillery, may lessen or destroy their usefulness. In general, the best results will be ob- tained when the infantry commander indicates or assigns XIII— 6-7 210 TACTICS AND TECHNIQUE— ARTILLERY a mission from time to time, and leaves to the artillery com- mander all possible latitude and initiative in the technical execution of this mission. Moreover, such a procedure will relieve the infantry commander of much of the burden which otherwise would be imposed upon him, and for which he has not time. Unless conditions make it inadvisable, the artil- lery commander should be given orders sufficiently general to permit him to attack favorable targets on his own initia- tive; this will not prevent the assignment of specific mis- sions by the infantry commander at any time, and may avoid keeping the guns idle for lack of an assigned mis- sion. (b) Although it is desirable to allow the artillery com- mander full latitude in details, the infantry commander should feel free to give corrective instructions at all times, even though contrary to the views of the artillery comman- der. 7. Missions. — (a) The missions properly assigned to an accompanying battery include those ordinarily incident to the support of infantry by light artillery; the only limi- tation is that the extent of the mission should be within the capabilities of the amount of artillery available; on this point, the infantry commander always can secure the advice of the artillery commander. Ammunition cannot be ex- pended in the lavish manner ordinarily possible for the divi- sion artillery as a whole ; this usually precludes firing at other than definite targets; barrages and the searching of large areas are too costly in ammunition. (b) The accompanying gun must be used still more sparingly; not only is its ammunition supply limited, but its advanced position makes it extremely vulnerable. When once it opens fire, it must obtain effect rapidly or it probably will be silenced and possibly destroyed. It is, in fact, an emergency weapon, to be used for those targets requiring its power and which cannot be attacked successfully by the infantry weapons. It should not be spared, however, at the expense of infantry casualties. Typical targets would be hostile strong points, machine guns, single field guns, anti-tank guns, and tanks used in counter attacks. XIII — 7-8 ACCOMPANYING BATTERIES— GUNS 211 (c) From the purpose of accompanying batteries and accompanying guns, it is evident that their targets ordin- arily should be those hostile elements immediately opposing the infantry advance. The idea that they fire habitually on targets which are beyond the range of the infantry special weapons is erroneous. (d) Accompanying artillery is detailed for special use in the attack, but may become an important element in the temporary local defense when the attack loses its driving power, particularly to assist in stopping a counter attack. In this case, the facility for close observation of the enemy’s attack affords an opportunity for the accompanying artil- lery to secure very prompt and accurate fire, sometimes more quickly and probably more effectively, than can be delivered by the supporting artillery. 8. Handling and Maneuvering of Accompanying Artillery. — (a) The handling of both accompanying bat- teries and accompanying guns puts to the severest test the skill of the officers and the training of the units. Prime re- quisites are reconnaissance, mobility, skill and rapidity in firing, and, at all times, boldness without rashness. Move- ment over exposed areas and difficult terrain is unavoida- ble, but delay and danger from hostile fire can be lessened by timely reconnaissance and suitable gaits and formations. Accompanying guns can be bolder than accompanying bat- teries; vulnerability increases and mobility decreases with the size of the unit. It is desirable to occupy positions as far advanced as possible ; but the extent to which this will be possible will depend on various factors, such as the diffi- culty of the terrain and the cover it affords, the resistance offered by the enemy, particularly in artillery fire, and the conditions of visibility. Accompanying guns ordinarily can push farther forward than accompanying batteries. Changes of position should be as few as possible, compatible with close support. (b) In some cases, readiness for close support is ob- tained by taking advantage of cover in the terrain in the locality of the assaulting battalion; in others, it must be obtained by seeking cover for the gun farther to the rear and by running forward wire lines for use from a temporary XIII— 8 212 TACTICS AND TECHNIQUE— ARTILLERY observing station nearer the assaulting troops, care being taken not to allow the wire line (which is apt to be cut by projectiles at any moment) to become too long.* (c) In firing, observation is essential, preferably from a point as near as possible to the pieces, so the guns can be commanded by voice. The artillery commander must be where he can command his guns or gun effectively; in addi- tion, it is desirable that he be with the infantry commander ; if both conditions cannot be fulfilled, he remains with his guns and connects with the infantry commander by tele- phone, or other means, and by liaison agents. If communi- cations are allowed to become long and complicated, or if the observation is distant from the guns, they lose their peculiar effectiveness, have little or no advantage over the supporting artillery and have some disadvantages. (d) For accompanying batteries, indirect laying from concealed positions is the rule, but not an invariable one; there are instances of batteries going into action in the open with excellent effect and without losses. The catchy French saying, “A battery seen is a battery lost,” is not always true ; it depends on who sees it and to what extent he is in a position to inflict damage. Accompanying batteries or- dinarily should be able to fire at ranges of less than 2500 yards. Positions, when initially occupied, may be very ad- vanced, there being instances, in our operations, of as much as a battalion of light artillery taking position considerably less than 1000 yards behind the infantry front line. Ac- companying guns are kept concealed as far as possible at all times ; occasionally during movement, and frequently in firing, they must be exposed. It is to be expected that such exposure will draw hostile artillery fire, and the gun must be moved to cover quickly and a new position used for sub- sequent firing. The range usually is short, say under 1500 yards, and the elevation so small that very little defilade is possible, even if it were desirable to use indirect laying. In some cases, the speed and simplicity of direct laying makes *A conception that “by accompanying guns is understood a gun carried along with or nearly with the infantry first wave” is errone- ous, and, in The World War, resulted, in several cases, in the gun being put out of action promptly. XIII— 8-9 ACCOMPANYING BATTERIES— GUNS 213 its use advisable. Whichever method of laying is used, the defilade is little or nothing. (e) Accompanying batteries use shell or shrapnel, de- pending on the missions. Many missions of accompanying guns also would call for the use of shrapnel ; the shell seemed to be preferred in service, however, because of the simplic- ity and speed of handling it. A few well placed projectiles of either type ordinarily will be effective. (f) In using accompanying guns, it often is neces- sary to use man power in assisting them over bad places. As a rule there will be sufficient artillery personnel for this purpose. At times, however, it may be necessary to call on neighboring troops for assistance. 9. Units From Which Accompanying Artillery Should be Detailed. — (a) When there is ample light ar- tillery from which to choose, the question may arise as to whether to detail accompanying artillery from that belong- ing to the division which employs it, or whether to detail it from other available sources. The objection to breaking up the organic artillery of the division is that the perman- ent team is partially destroyed : on the other hand, the ad- vantage in so doing is that the accompanying artillery thus obtained (which should be but a relatively small propor- tion) remains to fight with units with which it has already trained, and this permits a closer cooperation with the in- fantry to which it is attached. The latter method is recom- mended in the general case. (b) Accompanying batteries and accompanying guns should be provided with a full, or extra, quota of specialists for information (scouts). While the artillery commander should have access to all information possessed by the infan- try commander, frequently this information is inadequate from the artillery point of view. Artillery scouts, and sim- ilar personnel, should be employed freely as far forward as the infantry front line ; this personnel is also necessary for reconnaissance before or during movements of the artillery. (c) Cases may arise in which it is foreseen that accom- panying artillery will be needed when the infantry reach a certain stage of the advance. In such cases, the general practice should be to send accompanying batteries forward, XIII— 9-12 214 TACTICS AND TECHNIQUE— ARTILLERY as such, with orders to report, at a definite time or place, to the proper infantry commander. If accompanying guns be used, they should be detached ordinarily from the ac- companying battery, as required, accepting the principle that it is easy to detach the smaller unit from the larger one, whereas it would be difficult to assemble dispersed guns into an accompanying battery, if such were considered to be the tactical unit momentarily desired. (d) Cases may develop in which an accompanying bat- tery may detail a single gun or platoon to attend to a very local situation, with orders for such detached part to rejoin immediately on the execution of its mission. 10. Moral Effect of Attached Artillery. — T he moral effect of accompanying artillery on infantry is a fac- tor to be considered. The Chief of Artillery, 1st Army, A. E. F., stated: “The mere presence of accompanying pieces frequently has a moral effect upon the infantry quite dis- proportionate to the services they actually render. Infantry which has been ably supported by artillery soon gets a feel- ing of confidence in the mere proximity of that arm, which has a direct reaction on their own performances. Such a feeling is worth a great deal.” 11. Attached Artillery Drawing Fire. — There have been instances in which infantry commanders objected to the presence of artillery, and similar special weapons, on the ground that they drew hostile fire to the infantry. It should not be difficult to dispose infantry reserves so as to avoid close proximity to these weapons; in this case, fire received by the artillery should save the infantry casualties, to say nothing of losses inflicted on the enemy by these weapons. 12. Equipment of Accompanying Artillery. — The difficulties encountered in moving accompanying guns, and of supplying them from the rear, together with the animal casualties to which they are subjected, usually make it ad- visable to equip them specially. The following equipment has been used : 1 gun. 2 caissons. 1 extra team, 6-horse. Ample telephone, visual signal, and pioneer equipment. XIII— 12-14 ACCOMPANYING BATTERIES— GUNS 215 Accompanying batteries ordinarily carry only the us- ual equipment. 13. Suitability of 75-mm. Gun for Accompanying Gun. — The objection frequently is raised that the 75-mm. gun is not adapted for use as an accompanying gun, and that a more suitable type should be introduced. A self-pro- pelled 75-mm. gun on a caterpillar mount has been sug- gested; in other words, an unarmored tank, as far as ma- teriel is concerned. At the time the armistice was signed, preparations were actually in progress to use the service 75-mm. mountain gun as an accompanying gun. Since the accompanying gun is used only exceptionally, and, in using it, the limitations of the materiel can be taken into consid- eration, it hardly seems warranted to introduce a special type of materiel for this purpose, particularly as long as the infantry has special weapons as at present. More pow- erful infantry weapons might obviate the necessity for ac- companying guns from the artillery, at least to some ex- tent. The presence of tanks influences the necessity for us- ing accompanying guns, but the two weapons are by no means alike in their capabilities, at least at present. 14. Necessity for Combined Training. — The full effectiveness of accompanying batteries and accompanying guns cannot be developed merely through a high state of individual knowledge and training on the part of the infan- try and artillery; a teamplay is. necessary which can be at- tained only by the two arms working together. This com- bined training should be acquired in the training area rather than on the battlefield. XIV — 1-2 CHAPTER XIV Division Artillery in the Offensive Paragraphs Section I. • — General 1-19 Section II. — Meeting Engagement 20-28 Section III. — Attack of Enemy Deployed for Defense 29-80 Section IV. — Attack of a Prepared Position 31-34 Section V. Attack of a Defensive Zone 35-37 Section I General General 1 Kinds of Fire Support 2 Tactical Employment of Fire 3 Preparations 4 Destruction — 5 Observation 6 Neutralization 7 During the Attack 8 The Rolling Barrage 9 Successive Concentrations 10 Other Concentrations 11 Counter Battery 12 Interdiction 13 Fire on Transient Targets 14 Positions 15 Forward Displacement ^ 16 Missions 17 Organization of Command 18 Limbers, Combat Trains and Field Trains 19 1. General. — Important results are obtained by the artillery only when it is employed in mass. Feeble or half- hearted employment of the artillery can help in no way. The “offensive spirit” — the desire to carry the fight to the enemy, must be felt by the artillery as well as by the infan- try. By reason of its characteristics, it assists the other branches in gaining that fire superiority which is so neces- sary for success in battle. 2. Kinds of Fire Support. — Support of the infantry, in the offensive, is given by means of: (a) Preparation: 216 XIV — 2-3 GENERAL 217 (1) Destruction of the enemy’s personnel, weapons, works, organizations, and communications. (2) Neutralization of the hostile personnel, and consequently, of his weapons, organizations and communications. (b) Direct support during the advance of the infantry by: (1) Concentrations on critical points. (2) Rolling barrage, covering the front of the attacking forces. (3) Neutralization of more distant points and of localities which are not to be attacked directly. (4) Neutralization of hostile batteries by counter battery fire. (5) Fire on transient targets. (c) Fire during the pursuit: (1) Pursuit by fire. (2) Interdiction of places which the enemy must pass in his retreat. (3) Close support of the pursuing force. 3. Tactical Employment of Fire. — (a) The tech- nique of the foregoing kinds of fire is discussed in Chapter V. The general tactical employment of these different fires will be discussed here, followed by a discussion of their ap- plication to various situations. The multiplication of names, with but slight differences in meaning, which came to be applied to artillery fires, during The World War, is to be regretted. An effort has been made, in this discussion, to avoid that tendency. The infantryman has but little inter- est in the name applied to a particular kind of fire. His concern is to get some fire there quickly and efficiently. The probability that the most efficient kind of fire will be deliv- ered, is greatest when the objective and its location are de- scribed and the choice of the kind of fire is left to the artil- leryman. (b) To some extent, the technical methods of artil- lery firing, which developed during The World War, were peculiar to and because of the special situation which existed on the western front during the long period of stabilization. A similar situation in future wars is by no means assured. The principle announced by the War Department and reiterated by The General Service Schools, — that our training should be based on open warfare situa- XIV— 3-4 218 TACTICS AND TECHNIQUE— ARTILLERY tions — applies with special force to the field artillery, which otherwise might tend to lose its mobility and flexibility. Therefore, the open warfare situation is discussed first. As the enemy’s position becomes stronger, due to artificial de- fenses which he has constructed, the need for artillery in- creases, but the technical and tactical methods which the artillery employs are only developments and refinements of those used in the open situation. 4. Preparations. — (a) During The World War, the length of time devoted to artillery preparation for an at- tack underwent marked changes. Rapidly increasing, through earlier years of the stabilized situation, it reached its height in the attacks by the allies in 1917. From that time to the close of the war, there was an equally marked reduc- tion — some attacks being made without any preparation preceding the assault. The factors which brought about this change were: (1) The opportunity for surprise, which had been abandoned by the use of a long artillery preparation, giving the enemy time to mass his reserves and artillery to meet the attack and to smother it. (2) The introduction and improvement of tanks, which over- came the difficulty of getting through the wire and relieved the artillery of much work. (3) Improvement in the technical handling of artillery which permitted it to open fire quickly, without revealing its presence prematurely. These technical methods have their greatest appli- cation in stabilized situations. (4) An increase in the number of mobile batteries and in the number of rapid fire guns, so that, in a few hours, there could be fired a quantity of ammunition equal to that which formerly was fired over a period of several days. (5) Improvements in and increased production of gas shells, which greatly increased the neutralizing effects of artillery fire. (6) The proved incompleteness of attempts at destruction, and the substitution of neutralization therefor. (b) The method now having the greatest weight of approval is a violent preparation of not to exceed six hours. During this time, the artillery attempts to destroy such ob- stacles as seem most likely to stop the infantry, especially those just in front of the enemy’s positions, where our in- fantry would be subjected to the fire of the defenders (who are at that time released for action by the lifting of our ar- tillery fire) and to neutralize the other elements of his de- fense. XIV— 5-9 GENERAL 219 5. Destruction. — Artillery may be required to open passages through the enemy’s wire* and to destroy those strong points which are the most important, or which would most impede the advance of our infantry. The breaches through the wire should form a wide furrow extending through all the enemy’s successive positions. To the divi- sion artillery are assigned the breaches in the nearer bands of wire. The longer range guns and howitzers of the corps and army cut those in the more distant positions. The 75- mm. field guns find their best use against wire which is on horizontal ground or on the forward slope. The howitzers are needed for the breaches in wire on the reverse slopes. Because of its accuracy, its large angle of fall and the large charge of high explosive carried, the 155-mm. howitzer is a very effective piece for wire cutting. While firing on the wire, the trenches just beyond also are being subjected to damage. 6. Observation. — Destructive fire should be observed whenever possible. If darkness, fog or other condition ren- ders observation impossible, an increased allowance of am- munition and time is made in order to compensate partially for the errors in the fire. A factor of safety then is applied to the expected results. 7. Neutralization. — Neutralization of the enemy’s personnel is obtained by fire of gas, shell, or shrapnel on the areas occupied by his command posts, batteries, trenches, centers of resistance, machine gun nests and probable as- sembly places of reserves. The object is to pin his men to the ground, force them to wear their masks, break down their resistance and render them inactive. 8. During the Attack. — The artillery then seeks to paralyze the defenders, holding them in position until they are struck by our advancing infantry. These fires com- prise the rolling barrage and successive concentrations, as well as fixed concentrations on points not to be taken direct- ly by assault. 9. The Rolling Barrage. — (a) This is a development of The World War, having first been used in 1915, and has *ln some cases it is practicable for the assaulting infantry to pass over the hostile wire, as did our troops at St. Mihiel and in the Meuse-Argonne. XIV— 9 220 TACTICS AND TECHNIQUE— ARTILLERY its greatest application in attacks against defensive zones. It required a great expenditure of ammunition (about a day of fire for each 2500 yards of infantry advance ; assuming an average rate of advance and of fire) . The present trend is toward a more restricted use of this form of fire. Having been ordered to fire a rolling barrage, the artilleryman is chiefly concerned in his ammunition sup- ply; the technical difficulties of firing such a barrage are few. (b) The 75-mm. guns, firing percussion shell, estab- lish the near edge or line of the barrage, which the infan- try follows at from 100 to 150 yards. This “line” has a depth equal to the zone of dispersion, approximately twenty- five yards at 1500 yards’ range, and one hundred at 6000. From fifty to a hundred yards in advance of this shell line, it is desirable to have a portion, perhaps one-third, of the 75- mm. guns fire shrapnel. The barrage should be further deepened to 1000 yards by the howitzers, which fire concen- trations on selected points from three to eight hundred yards beyond the line of shrapnel. These concentrations are for the purpose of increasing the time to which the enemy will be subjected to the barrage, thus inflicting casualties and shaking his morale, and reducing the enemy’s ability to fire through the 75s’ barrage. They are fired best by search- ing the area forward and backward, that there may be no place within the limits of the barrage free from danger. (c) The density of the barrage, to be effective for the 75-mm. guns, should be twelve to twenty shots per minute for each one hundred yards of front. The rate of advance is fixed by the division commander according to the rate of advance expected of the infantry; one hundred yards in from three to ten minutes, depending on the expected re- sistance and the terrain. The bounds, in range of the guns, should be fifty yards to obtain the best results. (d) The barrage furnishes material and moral assis- tance to the infantry but limits its rate of advance. Herein lies one of the greatest difficulties — to foresee the proper rate of advance. Necessarily, it cannot be uniform through any considerable depth, since the conditions will vary so XIV— 9-11 GENERAL 221 greatly. Two general methods have been used in advancing the barrage : (1) Basing it on a time schedule made up for the entire ad- vance. (2) Having it move on a time schedule through stages of fixed depth ; halting upon definite lines until the commander directs it to proceed through the next stage, and then moving again at the predetermined rate. The first method obviates all reliance on communications. The second method gives the commander control of the barrage, enables the infantry to keep up with it and, by reducing the rate of fire during the halts, enables the artillery the better to maintain the desired density during the periods of its advance. The first method is the only one advocated at present. 10. Successive Concentrations. — By this method of support, only the points in the hostile terrain which are known or suspected to be held are subjected to fire. It is, therefore, much more economical in the expenditure of am- munition. When possible, it should be observed fire. For a given expenditure, it should secure greater material re- sults than the barrage. However, it does not furnish the moral support which the barrage gives to the advancing in- fantrymen. The concentrations of the 75-mm. guns should be kept at least 150 yards ahead of the infantry, by lifting the fire to the next objective when the infantry is about to enter the danger zone of the first. The howitzers fire on more distant objectives, or on those to which their fire is better suited. A schedule of these fires is prepared for each artillery unit, showing the approximate time of firing on each point. The rate of advance of the infantry will not be uniform over different parts of the front or at different times, hence the actual time for lifting the fire from any objective is subject to alteration — this on signal from the infantry, or by reason of the results of observation by the artillery officers. This is not open to the same criticism as that given above, on a barrage controlled by the infantry regiments, for the reason that the successive concentra- tions are observed fires, whenever possible, and the entire front is not covered by fire, leaving room for the infantry to maneuver around the centers of resistance on which the concentrations are placed. In the great majority of cases, successive concentrations are preferable to barrage fire. 11. Other Concentrations. — In addition to those fired successively in front of the infantry advance, concen- XIV— 11-13 222 TACTICS AND TECHNIQUE— ARTILLERY trations may be required, for predetermined periods, on strong points on the flanks of the advance. The infantry causes the fall of these points by outflanking them, and is supported in this by the artillery, which neutralizes the personnel occupying these localities. Smoke may be used in this case to blind hostile observation posts. If a locality is not to be occupied by friendly troops, persistent gas fur- nishes an efficient means for neutralization. 12. Counter Battery. — If an attack is to succeed, it is necessary to gain fire superiority. Especially must the friendly artillery dominate that of the enemy, else the ad- vance of the infantry may be stopped by hostile artillery fire alone. The mission of countering the enemy’s artil- lery is the function of the corps artillery, assisted by the army and, sometimes, by the division artillery. If the divi- sion is acting alone, but has attached a regiment of 155-mm. howitzers, the counter battery work would be undertaken by that regiment. Without the howitzers, this work must be done by the 75s. The employment of gas shells affords a means of neutralizing hostile batteries, which has re- placed the former attempts to destroy them by high explo- sive shells. The neutralization begins with the preparation and extends throughout the attack. Each hostile battery which discloses its position should be taken under fire at once, the fire being continued until the battery is silenced. For this reason, it is necessary to have batteries avaliable to answer calls for counter battery during the action. 13. Interdiction. — The purpose of this fire is to dis- rupt the enemy’s system of communications ; both on roads leading to his rear areas, and on the lateral roads. Interdic- tion is fired on places which the enemy is obliged to pass, such as a bridge or other defile ; crossroads ; the boundary of the zone of action of the troops making the attack, to pre- vent troops of adjacent sectors from reinforcing the attack, and sensitive points within the enemy’s rear area, such as distributing stations, ammunition dumps, and camps. To be effective, these fires should be commenced at the begin- ing of the preparation and be continued, intermittently, throughout the attack. They are fired suddenly and vio- Xiv— 13-16 AMMUNITION 223 lently at irregular intervals, and are based on the known habits and dispositions of the enemy. The 75-mm. gun is effective for interdiction fires on points within its range, especially if a road can be enfiladed with observed shrap- nel fire. The more distant interdiction is done by the heav- ier, longer range artillery. 14. Fire on Transient Targets. — By transient tar- gets are meant those which are moving or able to move quickly. The missions during the preparation and the at- tack are fixed, in a carefully prepared operation, but there should always be some artillery units available to undertake the destruction of hostile troops discovered during the ac- tion. For this reason, some batteries or battalions are given the mission of responding to calls from airplanes for fire. These fires consist of sudden and violent bursts in the form of zone fire, searching the area in which the target is re- ported. 15. Positions. — In all offensive operations, the posi- tions of the artillery should be well forward. The offensive implies an advance on the part of our forces, hence, if the artillery is to render efficient support throughout the ad- vance, it is not only necessary that the guns should be placed where they can reach well into the enemy’s position at the beginning of the attack, but they also must be pre- pared to move forward with the advance and make their sup- port continuing. The difficulties inherent in this latter man- euver add to the necessity for advanced positions. 16. Forward Displacement. — (a) (1) The fire of supporting artillery becomes less effective as the infantry advance progresses in a successful attack. The causes of this decrease in effectiveness are due to increase in range and to the increased difficulties of ground observation. The increase in range results in an increased zone of dispersion and an increased angle of fall. These factors result in lessened ef- fect because of increased errors in the time fuse and of contrac- tion of the ground pattern of shrapnel, and because of decreased certainty of action of percussion shell. (2) The infantry has particular need of efficient artillery support at this time because it is apt to have become more or less disorganized in the course of the successful advance. Its danger from counter attack also is greater at this stage of the action. (3) The artillery meets this need by advancing to positions whence it can continue an effective support of the infantry. Xiv— 16-18 224 TACTICS AND TECHNIQUE— ARTILLERY (b) While moving forward, the artillery units are out of action. Therefore, only a part of the supporting artil- lery should move at one time, while the remainder continue their fire until the first units are again in position. The number of movements should be reduced to a minimum consistent with effective fire support, therefore, the bounds should be of as great length as possible. The number of units sent forward is limited to those for which an adequate supply of ammunition is possible. Provision is made for reconnaissance of routes and for overcoming the difficulties of a forward movement through the battle area. Engi- neers are attached to artillery units, when necessary, to as- sist in the forward movement. (c) If a plan for the forward displacement has been made before the beginning of the attack, the matter is greatly simplified ; it needs then only to be coordinated with the progress of the attack and with the actual conditions as they develop in the combat. The end sought is to have the maximum amount of artillery in position to support the infantry during its hardest tasks. In an attack against a defensive zone, these are during the assaults on the suc- cessive hostile positions, which are placed from 3000 to 6000 yards apart for the very purpose of necessitating this movement of the attacking artillery. 17. Missions. — The missions which the division artil- lery is best able to perform are : (a) For the light field guns — destruction or neutrali- zation of the hostile infantry, destruction of the lightly con- structed defenses, cutting breaches in the nearer lines of wire, direct support of the infantry by successive concen- trations or the rolling barrage. (b) For the 155-mm. howitzers, when attached, — de- struction or neutralization of the hostile infantry, destruc- tion of somewhat more elaborate works of defense, wire cutting, counter battery, concentrations beyond those of the 75s and to deepen the rolling barrage. They are especially needed for reaching reverse slopes which the guns with flatter trajectories are unable to strike. 18. Organization of Command. — (a) The artillery of the division is a highly concentrated and powerful force. AMMUNITION 225 In any concerted action of the division, it is held under the control of the division commander. To apportion it among the infantry units, under these conditions, is unusual and, in general, relatively ineffective. The usual practice is to direct that one regiment of light artillery support the at- tack of each infantry brigade. If the brigades attack with regiments abreast, this permits a further apportionment of one battalion of light artillery to support each infantry regiment. A howitzer regiment, if attached, usually sup- port s # the division as a whole. (b) When the action develops into isolated attacks, pursuit, or other operation of separate infantry units, com- mand must be decentralized, hence the necessary artillery units then are attached to infantry units and come under the control of their commanders. 19. Limbers, Combat Trains and Field Trains. — Field artillery must remain mobile if it is to carry out its mission. The preservation of this mobility depends upon the care and protection from hostile fire given to the means of transportation, and upon their proximity to the firing bat- teries. The location and formation of these essential ele- ments of the artillery depend on the character of the opera- tion and the cover available. To secure the maximum cover, and yet be able properly to carry out their functions, are the objects sought. In rapidly moving situations, it is es- sential that the limbers or tractors be so placed that they can be concealed from hostile ground and aerial observa- tion, and have free and prompt access to the gun positions. The distance from the guns, therefore, is controlled by the character of the terrain. The combat trains work forward from the ammunition distributing point to the battery posi- tions. When filled, they may be held under cover until the opportunity or need for resupplying the batteries arises. Their location is governed by the same considerations as govern the location of the limbers, free access to the gun po- sitions by covered approach being of greater importance, in this case, than proximity. Hence, in open warfare situa- tions, the combat trains often might be posted farther to the rear than the limbers or tractors, keeping close to the roads which lead to the front. The field trains of artillery Xiy— 19-20 226 TACTICS AND TECHNIQUE— ARTILLERY regiments are united under the supply officer. Their loca- tion in combat, and on the march, is controlled by G4. They maintain contact with the regiment by agents, pushing for- ward to supply the troops when permitted to do so. When the situation becomes stabilized, the necessity for having the limbers and combat trains in proximity to the battery decreases, while the danger from hostile aerial or long range artillery attack increases. In such situations, the limbers, combat trains, and field trains all may be held together, as was the custom followed during the stabilized period of The World War. All officers and men, not needed to 'fight the batteries, were held at these rear positions, where all administrative work was done. Section II Division Artillery in a Meeting Engagement "Paragraphs Position on the March 20 Advance Guard Artillery 21 Plan of Attack - 4 22 The Development 23 Counter Battery 24 Approach March and Deployment 25 Advance to the First Firing Position 26 The Attack Proper 27 The Pursuit __! 28 20. Position on the March. — The first phase of a meeting engagement comprises the action of the advance guard, and the reconnaissance carried out to secure that information which the commander requires before he can decide upon his general plan of action. When combat is im- minent, the artillery with the advance guard marches far enough to the rear to insure it's own protection ; while that of the main body marches well forward to insure its early entry into action. The commander of the artillery with the advance guard should be with the advance guard com- mander, while the artillery brigade commander should be near the division commander, where their presence facili- tates the prompt receipt and exploitation of information. XIV— 21-23 DIVISION ARTILLERY— MEETING ENGAGEMENT 227 21. Advance Guard Artillery. — When contact with the enemy has been gained, the artillery with the advance guard should be placed promptly in position to support the advance guard in its covering action and reconnaissance, and, at the same time, to assist in covering the advance of the main body. Its missions during this phase depend upon the tactical mission assigned the advance guard. If that mission be to attack to secure favorable terrain, the artillery supports the advance of the infantry by concentra- tions on the hostile infantry, lifting on signal from the friendly infantry. If the mission of the advance guard be to hold defensively while the main body deploys; or to re- tire to a more favorable position, the artillery supports the action of the advance guard as in the defense or in a retreat, both of which situations are discussed in the next chapter. In any case, the main targets will be the infantry and ma- chine guns of the hostile covering force, either deployed or moving in small columns to positions — transient tar- gets. Prompt occupation of positions, skillful conduct of fire, by battery officers who are trained to select and apply the technical methods appropriate to the situation, good fire discipline on the part of the enlisted personnel and co- ordination with the infantry are essential to success. 22. Plan of Attack. — Based upon the information ob- tained from his advance guard and other sources, the com- mander of the column decides upon his plan of action. This being a consideration of the offensive, this plan is assumed to be to attack, hence would include the form and time of the attack, and the general employment of the artillery. 23. The Development. — A decision having been reached as to the plan of attack, the column is developed, clearing the roads so that the artillery with the main body may move promptly into position. The early entry of the artillery into the action not only covers the development and advance of the infantry, but also helps to clear up the situa- tion regarding the enemy’s dispositions and intentions. The positions should be well advanced. It may be necessary, however, to place some of the artillery units in action at once in order to bring some fire to bear on the enemy and to XIV— 23-26 228 TACTICS AND TECHNIQUE— ARTILLERY support the forward movement of the other artillery units. These units would be advanced to more forward positions at the first opportunity. The reconnaissance of routes and positions is started during the action of the advance guard, and the movement into positions otherwise is expedited in every way. This does not mean that the artillery moves forward at an excessive speed, but that by the proper re- connaissance, the establishment of communications and the preparation of firing data, fire can be opened as soon as the guns arrive in position. 24. Counter Battery. — It is probable that during the development, the hostile artillery will reply to the fire of our advance guard artillery, or will open effective fire on our infantry. Thus arises the early need for counter battery. If the division is acting alone, some of its batteries will have to undertake this work. The 155-mm. howitzer is an excel- lent counter battery weapon, and, when attached to a divi- sion, is used for this purpose. If no howitzers are available, the 75s are used to neutralize the fire of such hostile bat- teries as are inflicting losses on our infantry. However, the hostile infantry is usually the more important target. 25. Approach March and Deployment. — During these stages, the artillery preparation continues as during the development. All artillery units will have been assigned to support definite parts of the attack, and will have occu- pied their positions, prepared to assist in the concerted blow of the division. If the attack takes the form of an en- velopment, the artillery units supporting the secondary and main attacks should be so placed that they can assist each other. In this way, the division commander is able to shift the fire of the entire artillery to the points which appear vital to the success of the attack. 26. Advance to the First Firing Position. — (a) While the infantry is advancing to its first firing position, the artillery completes its preparation. It seeks to destroy any obstacles impeding the forward movement of the in- fantry. In a true meeting engagement, there are few of these obstacles, for the enemy has the opportunity to con- struct nothing more than hasty entrenchments. There may be rubble-stone or adobe walls, or hedges, in which the ar- Xiv— 26-28 DIVISION ARTILLERY— MEETING ENGAGEMENT 2 23 tillery can make openings and thus facilitate the advance. The main part of the preparation, however, consists in neu- tralizing the hostile infantry, machine guns and batteries ; using shrapnel, shell and gas for this purpose. The use of gas depends on the route of advance to be taken by our troops, and the time which will elapse before they reach the gassed area. The use of smoke shells, to blind the ene- my’s observatories during the preparation for the attack, may prove very efficacious. A few minutes before the in- fantry advances from its first firing position, the artillery increases its rate of fire and a heavy bombardment, by all the division artillery, is placed on the enemy’s front line infantry and machine guns, in order to shake their morale and to pin them to the ground during the advance of the friendly infantry. (b) The time available for the foregoing artillery pre- paration usually is limited to the time required by the in- fantry to deploy and advance to its first firing position. Necessarily, it is comparatively short. A prompt decision by the commander, and an equally prompt execution, are requisite for success in such a situation, hence a prolonged artillery preparation is unnecessary and undesirable. 27. The Attack Proper. — During the attack, the ar- tillery, by concentrations ahead of the advancing infantry, or by a rolling barrage, assists in overcoming the remain- ing resistance, and prevents the enemy from bringing up reserves, or from launching a counter attack. The infantry attacks by fire and movement; the artillery, attacking by fire alone, assists in gaining that fire superiority which ena- bles the infantry to reach a position from which it can make the assault. The decision as to whether successive concen- trations or a rolling barrage is to be used rests with the commander of the force, and depends on the character of the defense, the front to be covered, and the number of guns and amount of ammunition available. See par. 10. 28. The Pursuit. — When the enemy is driven from his position, artillery units sometimes are needed for attach- ment to the pursuing force. Here decentralization of com- mand is necessary, hence these units act under the direct orders of the commander of the pursuing force. The re- XIV— 28-30 230 TACTICS AND TECHNIQUE— ARTILLERY maining artillery units pursue by fire, placing concentrations on the hostile troops wherever seen, interdicting roads over which the enemy must retreat, and supporting the pursuing force by firing on the hostile rear guard. Section III Attack Against an Enemy Deployed for Defense Paragraphs The Situation I 29 Artillery Action 30 29. The Situation. — In this case, the enemy will have had more time to select his position and to strengthen it and will cover his main position by outposts. His artillery will be in position, with arrangements made for the resupply of ammunition, and will be prepared to fire on points on the ground over which the attacking forces must pass. 30. Artillery Action. — (a) The attacker's artillery is placed promptly in positions from which it can reach well into the enemy’s territory, in order to support the action of the advance guard, in driving in the enemy’s outposts, and to combat hostile artillery which opposes the approach and deployment of the friendly infantry. (b) The increased strength of the enemy’s position renders the task of the attackers more difficult, thus neces- sitating a more deliberate attack and more carefully planned details. This applies to all branches. The artillery prepara- tion may be longer and more methodical, but still will con- sist largely in neutralizing the hostile forces and weapons, and in preventing the enemy from further strengthening his position. During the attack proper, the artillery fires successive concentrations or a rolling barrage. The need for the latter method of support increases with the increase of strength in the enemy’s position, mainly because of the undeniable moral support the barrage gives to the attack- ing infantry. The ammunition supply, however, must be XIV — 30-33 ATTACK AGAINST PREPARED POSITION 231 one of the points considered by the commander in deciding on the method of artillery support. Section IV An Attack Against a Prepared Position Paragraphs Situation _ 31 Preliminary Action 32 Artillery Preparation 33 The Attack — 34 31. Situation. — The characteristics of this situation, which distinguish it from the preceding ones, are that the enemy has been longer in position and, so far as possible, has strengthened the natural advantages of the terrain. He will have constructed more and stronger field works, in- cluding several belts of wire ; his dispositions will have been made in greater depth; more complete provision will have been made for his ammunition supply; and his covering forces will have been pushed farther to the front and en- trenched. A powerful and concerted blow is essential to success in attacking such a position. Such a blow is possi- ble only after careful and deliberate preparation. 32. Preliminary Action. — During the action of the advance guard, in driving in the covering forces and recon- noitering the position, it may be necessary to reinforce the advance guard artillery to support the reconnoitering forces and assist in clearing up the situation. During this pre- liminary action, the troops of the main body are brought forward and massed under cover, awaiting the time for the attack. This gives additional time for the reconnais- sance and occupation of positions by the main part of the artillery. In order that the artillery fire may reach to the rear of the hostile position, it is necessary to place the artil- lery in positions well forward. 33. Artillery Preparation. — (a) In the usual case, the artillery preparation begins with the development of the XIV — 33-34 232 TACTICS AND TECHNIQUE— ARTILLERY infantry and continues until the time set for the attack pro- per, thus supporting the infantry during their approach march, deployment, and advance to the first firing position. The commander of the attacking forces decides as to the duration and intensity of the preparation, basing his deci- sion on the general plan of attack, the character of the de- fense, and the ammunition supply. The opportunity to strike quickly, which offers success in a meeting engage- ment, is not so apparent here. However, the commander may keep the enemy in doubt as to the time and direction of his main blow, and, to assist in this element of surprise, he may limit the artillery preparation to light harassing and interdiction fires, with a brief but violent preparation im- mediately before the attack proper. Or, if tactical and other conditions warrant the delay, he may wait for the cover of darkness to advance his infantry to the line of depar- ture for the attack. In this case, the advantages of keep- ing the positions of the bulk of his artillery concealed from the enemy, may cause him to limit the artillery prepara- tion. (b) During the artillery preparation, the missions of the division artillery are the destruction of the enemy’s light trenches and wire (tanks also are used for the destruc- tion of wire), and, above all, the neutralization of the hostile infantry and machine guns. Again, if the division is act- ing alone, some batteries will be needed for counter battery work, to neutralize the hostile artillery. 34. The Attack. — When the infantry advances from its first firing position, it is preceded by a rolling barrage or by successive concentrations of artillery and machine gun fire. If the front is too great to be covered effectively by a rolling barrage, it may be advisable to fire a barrage in front of the main attack with a majority of the guns while the others place concentrations in front of the holding or secondary attack. Xiv— 35-36 ATTACK AGAINST DEFENSIVE ZONE 233 Section V An Attack Against a Defensive Zone Paragraphs Situation 35 Artillery Action __ 36 Continuing the Support 37 35. Situation. — In this situation, which is the one which prevailed on the western front throughout the greater part of The World War, the enemy's system of defense con- sists of two or more positions, averaging about three thou- sand yards part, each position consisting of several lines of trenches and wire, strong points and centers of resis- tance being organized between these main positions. These positions are strengthened by all available means; troops are disposed in depth throughout the zone ; elaborate means of communications are established; and provision is made for an ample supply of ammunition. The attack of such a position is more difficult than that of one less highly or- ganized and requires more careful and detailed planning. The attacking infantry is assumed to be able to form for battle in its own trenches or under other cover near the ene- my's first position, or to be moved to such a position under cover of advance troops and darkness. The reconnaissance proceeds, perhaps for several days prior to the attack. After the artillery preparation, the infantry assaults the first po- sition, fights its way through the intervening area, assaults, the second position, and continues thus until the zone has. been broken through, or until the attack has been brought to a halt by the defenders. 36. Artillery Action.— (a) The fires executed by the artillery are: (1) Preparation — destruction or neutralization of the ene- my’s defensive works and weapons. (2) During the attack — successive concentrations or rolling barrage. (3) During the pursuit — concentration on hostile covering forces, and on retreating bodies of the enemy, and interdiction. (4) Or, defensive fire, during the organization of the new position. Throughout the entire combat, the artillery will have counter battery, interdiction, harassing and transient target mis- sions. Xiv— 36-37 234 TACTICS AND TECHNIQUE— ARTILLERY (b) The details of these fires are planned ahead so far as human foresight is able to suggest. Schedules are pre- pared, accompanied by maps or tracings, which show the objectives for each artillery unit, the time at which the fire on each is to be delivered, the number of rounds, the rate of fire, and the kind of projectile. The details for the roll- ing barrage are worked out by each lower unit so that each gunner has before him a sheet showing the data for each shot he will fire during the advance, and the time and rate of fire. Time is available for employing all possible refine- ments in calculating the data and in laying the pieces. Large quantities of ammunition are brought forward and placed near the guns. A schedule of forward displacement is drawn up, and missions from the new positions may be assigned. These plans may prove to be impossible of exe- cution, especially that of the forward displacement and sub- sequent missions. To modify a prearranged plan is rela- tively simple. To develop a new plan, during the course of battle, and to acquaint all concerned with its details, is rel- atively difficult. Hence the necessity for well developed plans, conceived in prevision of the probable course of the action. However, preconceived ideas never are allowed to prevent such changes of plan as are dictated by changes in the situation. 37. Continuing the Support. — It is not sufficient to take the hostile first positions only, for then the blow be- comes imbedded and the situation is favorable for hostile counter attacks. To secure the full benefit of the operation, the hostile rear position must be broken through and the enemy’s withdrawal closely followed and exploited. For this reason, the infantry attacks in depth, permitting the rear units to pass through those which have become worn and depleted, and to continue the advance. During the assault on the rear position, which is the critical phase of the attack, the artillery must continue to do its part by fur- nishing fire support to the infantry. The carefully planned support which they were able to give from their initial po- sitions, is now no longer possible, the infantry having ad- vanced beyond the range of the guns. Moreover, the at- tacking force will not be uniformly successful along the en- Xiy— 37 ATTACK AGAINST DEFENSIVE ZONE 235 tire front. A part of the infantry will push forward more rapidly than others and will assist in advancing the remain- der of the line by taking the points of greater resistance in flank or in reverse. These units require artillery sup- port operating under the direct control of the local infantry commander. If a sufficient number of guns is available, some artillery units may be directed to begin their advance as soon as the infantry starts from the line of departure, while the others support the attack with the rolling bar- rage and other fire. Some or all of the former units would participate in the artillery preparation, depending on the local conditions and necessities. As previously stated, those units which support the attack are pushed forward as rapidly as possible, after completion of that duty, to insure artillery support during the attack on the rear positions. But, in order to insure artillery support for the local com- bats above mentioned, accompanying batteries and ac- companying guns often are required. Their employment is discussed in Chapter XIII. XV— 1 CHAPTER XV Division Artillery in the Defensive Paragraphs Section I. — General _> 1- 9 Section II. — Defense in a Meeting Engagement 10-11 Section III. — Deployed Defense — Defensive Position 12 Section IV. — Defensive Zones 13 Section V. — Withdrawal and Retreat i 14 Section I General Paragraphs General Duties and Principles + 1 Methods of Support 2 Tactical Employment of Artillery Fire 3 The Defensive Barrage 4 Counter Preparation 5 Defensive Concentrations 6 Deployment 7 Missions 8 Organization of the Command 9 1. General Duties and Principles. — (a) An active defense seeks a favorable opportunity to strike a decisive counter blow; a passive defense seeks to deny the enemy a decision. In either case, the first step, in attaining its object, is to stop the advance of the enemy on, or in front of the defensive line or area chosen by the commander. Failing in this, the defense seeks to stop the enemy’s ad- vance as quickly as possible, to regain the lost position, to establish itself in a new position for defense, or to withdraw — following this latter by an orderly retreat, if necessary, in order to free itself from the pursuing forces. (b) The general purpose of the artillery, in the de- fensive, is the same as in the offensive — to support the other branches, especially the infantry. (c) The supporting fire of field artillery, on the ‘de- fensive, is fully as effective as on the offensive. It even may be more so, as instances have been noted in which a 236 XV— 1-3 DIVISION ARTILLERY IN THE DEFENSIVE 237 hostile advance has been stopped by artillery fire alone; whereas, good infantry cannot be driven from a position by artillery fire alone. (d) The principles of employing artillery fire in mass, quickly, and with precision, are the same as on the offensive. 2. Methods of Support. — The artillery supports the infantry in defense. (a) From the time when contact is first gained by: (1) Fire on transient targets, (2) Interdiction fire, (3) Harassing fire, (4) Destruction or neutralization of hostile batteries. (b) During the hostile preparation for the attack by counter preparation, consisting of: (1) Fire on hostile forming up places, and on probable posi- tions of hostile reserves, (2) Destruction or neutralization of enemy’s works, obser- vation posts, communications, (3) Counter battery, (4) Interdiction. (c) During the attack proper by: (1) Defensive concentrations and barrages; (2) Concentrations against advancing infantry, tanks and accompanying weapons; (3) Counter attack barrages or concentrations supporting counter attack. (d) During the withdrawal and retreat by: (1) Counter preparation against each phase of the attack; (2) Concentrations against the most advanced or most threatening elements of the hostile troops; (3) Interdiction. 3. Tactical Employment of Artillery Fire. — The employment of the above mentioned kinds of fire does not differ in principle from that of the offensive. Rolling bar- rages and successive concentrations are used by the defen- ders in making counter attacks, which are conducted ac- cording to the general principles of the offensive. The kinds of fire peculiar to the defense are the defensive or protective barrage, counter offensive preparation (or sim- ply counter preparation) and concentrations after the enemy has broken through the covering force. XV— 4 238 TACTICS AND TECHNIQUE— ARTILLERY 4. The Defensive Barrage. — (a) Before The World War, it was recognized that artillery on the defensive should take advantage of every opportunity to prepare data for fire on the probable routes of the enemy’s approach to the chosen position. During the winter of 1914-1915, the op- posing lines on the western front were very close to each other. The probable routes of the enemy’s approach cov- ered practically the entire front, though an advance by some routes naturally was more probable than by others. The hostile attacks, therefore, came quickly and at many different points. To break up these attacks, there was needed artillery fire which could be placed immediately upon the point from which the attacking infantry started. To meet this need, the defensive barrage was originated. Each battery of the division artillery is given a definite location upon which to place its normal barrage upon call from the infantry defending that part of the front. To cover the re- mainder of the front, batteries are assigned one or more eventual barrage lines. Barrages at first were placed on the hostile trenches, but later were drawn back and placed at about 150 yards in front of the line to be defended, these lines having been withdrawn, where necessary, to gain suf- ficient distance from the hostile line. The front to be cov- ered at one time, by a defensive barrage fired by a battery of 75-mm. guns, should not be greater than 250 yards. If less, the fire can be made correspondingly more dense and effective. 200 yards may be taken as the proper front un- der average conditions. An effective rate of fire, on such a front, is six rounds per gun per minute for the first four minutes, followed by two rounds per gun per minute for two minutes, or other suitable combination. The rate and duration of fire are prescribed in orders. The barrage must come down immediately on call from the infantry. For this reason, the batteries charged with these fires are kept laid on their normal barrage when not engaged in carrying out other suitable missions. An efficient system of visual signals and telephone communication, between the front line infantry and its supporting artillery, is, therefore, of utmost importance. (b) An attempt to secure the safety of the entire front, by means of simultaneous barrages, results in weakness at XV— 4-5 DIVISION ARTILLERY IN THE DEFENSIVE 239 all points. Hence, sensitive points between or in front of the centers of resistance are covered by the normal barrages, while the remainder of the front is covered by machine guns, rifles, and other infantry weapons, and by eventual artillery barrages. (c) While the division artillery is firing the barrage, the heavy and medium field artillery fire on critical points beyond the enemy’s front line, such as command posts, road crossings and trench junctions, and continue whatever counter battery fires may be undertaken. (d) In high repute during the winter of 1914-1915, the defensive barrage declined in prestige thereafter. From the experience gained in 1916 and 1917, it became evident that the barrage, effective only when fired immediately on call, rarely included the advance elements of the hostile at- tack. Moreover, having a depth equal only to the zone of dispersion, it may be shown that the probability of becom- ing a casualty by going through such a fire is not great.* Therefore, it is necessary to fire upon the enemy while he is forming for the attack and, also, after he has reached our first line. For this reason the counter preparation and (after the enemy has broken through our covering forces) the concentrations were developed and, to a great extent, replaced the defensive barrage. Its future use depends on the situation. When the lines become stabilized for some time, it seems probable that it may have frequent use, but defensive concentrations will have much more general ap- plication. 5. Counter Preparation. — (a) Broadly speaking, all fire of the defenders during the preparation of the attack may be called counter preparation; including a systematic bombardment of the hostile troops from the time they are first within range of the guns, counter battery, neutraliza- tion and destruction of whatever cover the enemy have. During The World War, the term counter preparation was used, in a more limited sense, to apply to the fires delivered to break up the hostile attack formations near the enemy’s front lines. By subjecting his troops to fire during the time * Under average conditions of rate of fire, and rate of infantry advance, the probability is about 11 per cent. XV— 5-6 240 TACTICS AND TECHNIQUE— ARTILLERY he is forming for attack, his dispositions are broken up and the morale of the attacking force impaired before the at- tack can be launched. Therefore, these fires are placed on his front line trenches, on woods and ravines which offer cover for assembled troops, and on all points probably occu- pied by his formations. For every hostile fire put down by the enemy in preparation for his attack, an equal and cor- responding fire is placed on a point within the enemy’s lines opposite the probable point of attack. For defense against local attacks, partial counter preparation is fired, covering only the threatened points ; if a general attack appears pro- bable, a general counter preparation, covering the entire division front, is needed. Tables or plans for these counter preparations are prepared, based on all probable methods of attack, and are given a designation by number or letter. These fires are held on the designated points for the period prescribed in the plans — usually about fifteen minutes. They must be precise, quickly brought down, and of sufficient in- tensity to accomplish the purpose. The average rate of fire is two rounds per gun per minute for 75s and from 30 to 40 rounds per gun per hour for 155-mm. howitzers. After firing the counter preparation, batteries must be able to change quickly to the defensive barrage, when that method of fire is to be used. (b) When the division is part of a corps or larger force, the corps and army artillery are given the more distant missions in the counter preparation. 6. Defensive Concentrations. — During all of his advance, both before and after reaching the position held by the defenders’ outposts, the enemy must be subjected to all possible artillery fire. Between the defenders’ centers of resistance, there will be lanes through which the enemy will advance more rapidly than at other points. To cover these lanes of advance up to the main line of defense, con- centrations are prepared. They are fired when the friendly infantry, or observation, indicates that the enemy is in the predetermined locality. These fires must have sufficient depth to include all of the advancing element, not merely the heads of the columns. If the attack penetrates the main line of resistance of the defenders, these fires are continued on XV— 6-8 DIVISION ARTILLERY IN THE DEFENSIVE 241 the lost ground, care being taken to coordinate them with any counter attack which may be launched. Whenever pos- sible, observed fire will be used in such defensive concentra- tions. 7. Deployment. — The basic principle which governs the selection of positions for artillery, in all situations, is that it be able to carry out the mission assigned it. In the offensive, that mission being to support the infantry ad- vance against the hostile position, the artillery is placed generally well forward. In the defensive, the mission is to assist the other arms in stopping the enemy’s advance. The commander having chosen the line or lines to be defended, all the artillery is placed in rear of these lines to assist in their defense. The desire to bring the full power of all the artillery to bear, in the defense of the main line of resis- tance, and to continue this defense without interruption, after the enemy has driven in or broken through the cov- ering forces, tends toward a selection of positions in rear of this main line of resistance. On the other hand, the out- posts must be covered by artillery fire, the defensive bar- • rage and counter preparation missions must be carried out, and some batteries must be able to reach well into the ene- my’s lines to break up his formations, counter his bat- teries and interdict his lines of supply and communication. The conflicting considerations lead to a deployment of the artillery in depth; applicable to division, corps and army artillery. Such dispositions also permit the advance ele- ments of the artillery to be withdrawn, should the necessity arise, under cover of the fire of the units farther to the rear. The most advanced elements should be those which have the greatest mobility, so far as the proper assignment of missions will permit. 8. Missions. — The missions properly assigned to the division artillery are: (a) For the 75s — defensive barrages in front of the outpost and other lines, counter preparation to a depth of 1500 yards in rear of the enemy’s front line, defensive con- centrations on the areas between the position of the cover- 242 TACTICS AND TECHNIQUE— ARTILLERY in g force and the main line of resistance, counter attack con- centrations and barrages,* and fire on transient targets. (b) For 155-mm. howitzers, if attached — same as for the 75s, deepening the beaten zone within the enemy’s line to a depth of 5000 yards or .such other extension as the power of the howitzer justifies. 9. Organization of the Command. — The necessity for concentrating the fire of all or a part of the division artil- lery, and the opportunity afforded for establishing an effi- cient system of communication, indicates the desirability of retaining the artillery brigade under command of the division commander. Artillery support must be given promptly to the different infantry units. Therefore, the 75 regiments usually are assigned to support particular infantry brigades, regiments or portions of the line to be defended. The howitzer regiment, if attached, usually is placed in general support of the entire position. Calls for fire from infantry units (battalions or regiments) are made direct to the supporting artillery unit. The latter furnishes the desired support or calls on a reinforcing artillery unit. Liaison officers from the artillery are sent to infantry bri- gades, regiments and battalions : it is through those officers that calls for support should be made. Section II The Defense in a Meeting Engagement Paragraphs • Situation 10 Action of the Artillery 11 10. The Situation. — (a) When contact with the ene- my has been gained, the artillery of the advance guard is placed promptly in position to assist in carrying out the mission of that covering force. This mission is based on the orders or intentions of the division commander, and, as we have seen in the offensive, may be : ♦The rolling barrage as in the offensive. XV— 10-11 DEFENSE IN MEETING ENGAGEMENT 243 (1) To advance and seize favorable terrain, upon which the division will make its defense; (2) To hold defensively the terrain then occupied; or (3) To delay the enemy while withdrawing to a position farther to the rear. (b) In the first case, the local action is an offensive op- eration and is conducted on the principles which govern in such combat. In the third case, the action is similar to that in a withdrawal or retreat, which is discussed later. The second case, being purely defensive, will be discussed here. 11. Action of the Artillery. — (a) In this situation, the artillery of the advance guard is so placed as to cover not only the immediate front of the chosen position, but also to reach well into the enemy's terrain to cover his lines of approach, cause early deployment and delay the hostile advance, and break down the attack of the hostile covering force, if one be made. This requires a deployment in depth within the unit itself. Missions and sectors of fire must be assigned promptly to the smaller artillery units. During the development of the defenders, the artillery marching with the main body is placed in position. It may be advisa- ble to hold a part of the artillery in positions in readiness or in observation until the direction of the hostile attack be- comes known. In this case, energetic reconnaissance and preparation for probable situations should be pushed. Artil- lery regiments are assigned general localities for positions and given the mission of supporting certain infantry units or portions of the defensive line. The principle of deploy- ment in depth is adhered to. When communications are dif- ficult, and command is of great importance, as they are in this case, it is well to echelon the battalions, keeping the batteries of each battalion fairly close together. The longer the position is occupied, the more the batteries within the battalion will be echeloned. (b) The decision to assume the defensive, generally, though not necessarily, is taken to indicate an inferiority in strength, including an inferiority in artillery. The hostile attack can have no decisive success if the advance of the infantry can be stopped. Therefore, the defenders' divi- sion artillery should be used against the hostile infantry, cavalry, tanks and accompanying weapons, and should not XV— 11 244 TACTICS AND TECHNIQUE— ARTILLERY allow itself to be drawn into an unequal contest with super- ior artillery strength. If enough guns are available, some may be assigned the duty of replying to the hostile batteries and neutralizing their fire, but the principal target for the artillery on the defensive, especially the division artillery, is that portion of the enemy’s attack which most threatens our position, — usually the advancing troops with their ac- companying weapons. (c) The time for opening fire depends on the enemy’s advance. It is prescribed in the orders of the artillery com- manders. It may be desirable to withhold the fire of some batteries, especially if the enemy is much superior in ar- tillery, until the attack has reached a more vulnerable stage in its deployment and approach. In the situation under dis- cussion, no opportunity will have been offered for the pre- paration of fires before the beginning of the action. Within its sector of fire* each artillery unit seeks to inflict casual- ties upon and to stop the advance of the enemy during his approach march, deployment and advance to his first firing position. Each unit should be able to fire in the adjacent sectors thus enabling artillery brigade, regimental and bat- talion commanders to coordinate the fires of their command, or concentrate them on the most threatening part of the ad- vancing force. When the enemy begins the advance from his first firing position, it is especially important that the ar- tillery direct its fire against the advance waves of the at- tack. This fire should be placed short enough to include the leading elements, and also should have sufficient depth to in- clude the local supports and reserves. Coordination with the friendly infantry is necessary during its withdrawal from the covering or advance positions. If the attack breaks through the position, the artillery continues to fire on ad- vancing hostile infantry, assists in counter attack, or covers the withdrawal. xv— 12-13 DEPLOYED DEFENSE— DEFENSIVE POSITION 245 Section III Deployed Defense — Defensive Position Paragraph Deployed Defense — Defensive Position *_ 12 12. Deployed Defense. — Defensive Position . — When on the defensive, every opportunity is grasped to strengthen the natural defensive features of the terrain, and to prepare systematic plans for the defense of the position. The artil- lery does this by preparing firing data and registering fire on points on the ground over which the enemy must advance to the attack, by getting forward the necessary supply of ammunition, by establishing systems of communications by all possible means, by concealing its position by natural and artificial means, and by constructing cover for the per- sonnel, ammunition, and guns. The degree of refinement to which these preparatory measures are carried, depends on the plan of the commander, the energy and resource- fulness of the artillery personnel, and the time available between the selection of the position and the hostile attack. When there has been time merely to deploy, these arrange- ments are meager: when ample time is available, the posi- tion may develop into a defensive zone, the artillery making correspondingly detailed preparations. Between these two extremes, there are many variations ; the employment of the artillery varies in the same way. Section IV Defensive Zone Paragraph Artillery Positions 13 13. Artillery Positions. — (a) (1) The positions assigned the division artillery are such that it can support the defense both of the main line of resistance and of the outpost line. XV— 13 246 TACTICS AND TECHNIQUE— ARTILLERY (2) The following are the factors which determine the limits within which the division artillery is placed: (a) The forward limit is determined by the fact that the 75s are most effective when not closer than 1500 yards to the line to be defended. This is because of the flat trajec- tory. With reduced charges, this distance can be reduced to 800 yards. (b) The rear limit is determined by the fact that counter preparation is essential to a depth of 1500 to 2000 yards within the enemy’s lines. Hence the guns are placed not more than 5000 yards in rear of the outpost line of observa- tion. (b) The general location of the artillery having been decided upon, battalions and batteries are so located as to take full advantage of the terrain in that vicinity. Units are echeloned in depth so as best to carry out the missions assigned them, and to cover the withdrawal of the more for- ward units, should that become necessary. Some guns from each battery usually are placed in forward positions to carry out the more distant missions during the time of compara- tive inactivity prior to the attack. When it is apparent the attack is about to begin, the guns usually are withdrawn to normal positions if practicable. Batteries often are prohib- ited from firing from their normal positions except in case of a serious attack, in order to keep those positions hidden from the enemy and prevent the destruction or neutraliza- tion of the batteries by the hostile artillery. Alternative positions, 500 yards or more from the normal positions, are reconnoitered and prepared for use in case the normal posi- tions are neutralized. Single pieces, for defense against tanks sometimes are detached and posted well forward, covering routes of approach. During periods of relative inactivity, other pieces, called roving guns, are sent from place to place to conduct fire, thus carrying out assigned missions and, at the same time, deceiving the enemy as to the exact amount and location of the artillery. XV— 14 WITHDRAWAL AND RETREAT 247 Section V Withdrawal and Retreat Paragraphs General Discussion 14 Fires 15 14. General Discussion. — Because of its range, artil- lery is particularly valuable in a withdrawal and in a re- treat. Because of its close relation to the infantry, its mobility, and the rapidity with which it can open fire from a new position, much of this duty devolves upon the divi- sion artillery. Some artillery units are attached to the force which covers the withdrawal, the others, from positions far- ther in rear, support the covering force and cover its later withdrawal. The movements of the artillery are based upon the general plan of maneuver and are coordinated with the movements of the infantry. Its displacements may be made on direct orders of the commander of the force, or, preferably, on a prearranged plan. A plan of withdrawal, when the necessity therefor can be foreseen, is even more necessary than one for a forward movement, because the execution of such a maneuver is more difficult, owing to the lack of communications and the decreased morale. This plan should be supplemented by a detailed reconnaissance of routes and positions, which can be made readily, since the terrain lies within one’s own lines. The extent to which such a plan should be communicated beforehand to subor- dinates must be such that it will not result in lowering the morale or causing a premature movement. The changes of position are made by echelon — frequently by separate bat- teries within the battalion. Command is decentralized be- cause of the lack of communications and the rapidly chang- ing situation. For the purpose of command, it is essential that artillery command posts be located near the firing bat- teries; for the purpose of coordination with the infantry, and the prompt and efficient exploitation of information, these command posts should be near those of correspond- ing infantry commanders. These two requirements, some- times conflicting, must be adjusted. The infantry can as- XV— 14-15 248 TACTICS AND TECHNIQUE— ARTILLERY sist in this by keeping the artillery in mind when locating its command posts. Observation posts must be as near the batteries as the terrain will permit. 15. Fires. — (a) The fires conducted by the artillery, during a withdrawal and retreat, are intended for the de- struction of enemy personnel and delay of hostile pursuit and consist of counter preparations for each position occu- pied during the retreat, concentrations on each attack which may be launched, and interdiction to prevent the resupply of food and ammunition to the enemy. Establishing a new defensive barrage line for each successive position is not practicable. Most of the objectives will be transient targets — small groups of the enemy which filter through the points of least resistance. The artillery, by observation, must place its fire upon the enemy and not upon ground he does not occupy. The preparation of firing data for probable routes of advance, however, will enable the fire to be shifted promptly and placed as conditions require. The opportunity for this never is neglected. Persistent gas is used to the maximum. (b) The artillery exerts every effort to obtain infor- mation concerning the immediate situation rather than wait for this information and for calls for fire to be given to it by the infantry. If fire is withheld until called for, it is probable that its effect on the operation will be small. (c) In covering a retreat, it is sometimes necessary for artillery to be sacrificed. When the occasion demands, there should be no hesitation in taking such action. XVI— 1-2 CHAPTER XVI Artillery Combat Orders Paragraphs Artillery Provisions of Army and Corps Orders 1 Artillery Subparagraph of a Division Field Order 2 Field Order of the Field Artillery Brigade 3 Artillery Annex to the Division Order 4 Orders of Regiments and Subordinate Units 5 Use of Maps and Charts 6 1. Artillery Provisions of Army and Corps Orders. — Army orders covering any deliberate attack or defense normally are accompanied by an artillery annex (with ap- propriate maps, charts, and tables) fixing the missions of the army and corps artillery, and allotting additional artil- lery units to the several corps, according to requirements. The artillery paragraph, with its annex, prescribes the de- tails essential to successful cooperation between the army artillery and that of the several corps, and fixes their mis- sions, target areas, and general locations. In like manner, each corps issues a corresponding annex, in which the re- quirements, in the artillery paragraph, are developed so as to establish fully the character of all artillery support within the corps, provide for counter battery work, provide for cooperation between the corps artillery and that of the divisions, and provide for mutual support to be afforded by the artillery of adjacent divisions. When necessary, the corps artillery brigade issues a brigade field order, which is an order to the units of that brigade only. 2. Artillery Subparagraph of a Division Field Or- der. — (a) In general, the artillery paragraph of the divi- sion order is written with a view to giving the infantry com- manders all necessary information in regard to the contem- plated artillery action and support. Furthermore, this paragraph is sufficiently definite and complete to afford the artillery brigade commander a basis upon which to formu- late his detailed order. 249 XVI— 2 250 TACTICS AND TECHNIQUE— ARTILLERY (b) The artillery brigade commander, as the artillery advisor of the division commander, generally is consulted in drafting this paragraph; but, when issued, it comes to him as a commander of artillery, and is his authority for his brigade order, just as the infantry paragraphs are the authority upon which the infantry commanders act. (c) This subparagraph (of paragraph 3) normally contains instructions as to assignments, general missions and fires to be executed, general artillery locations, special duties, and the use of smoke and gas (in case they are to be employed). There may be some caution as to prepara- tion for future movements. In case of movements actually ordered — such as movements to initial positions — routes are designated or the responsibility for selection of routes de- finitely fixed. (d) As an illustration, the following is given as a form that might be used in an attack order : (c) (1) The 1st FA Brig, with the 101st FA attached, will support the attack: the 1st FA supporting the 1st Brig from positions near ; the 2d FA supporting the 2d Brig from po- sitions north of ; the 101st FA supporting both brigades from positions in the vicinity of . Sup- port will be by (successive concentrations, or other fires). Special attention will be paid to (support of certain friendly units — or their sectors — or designated important points in hostile territory). (2) An artillery bombardment of enemy front lines, participated in by all available guns, will begin at . Prior to this, artillery fire will be (reduced to a minimum, confined to registration and light harassing, etc.). Fire on front lines will be lifted (infantry signal or stated time). (3) Smoke and non-persistent gas will be used (areas). The use of smoke (gas) along boundaries will be regulated by (commanders 1 concerned) . (4) For further details see Annex No. 1. (In case an artillery annex is issued.) (e) The above is about the average amount of detail found in an order for an attack in a normal (warfare of movement) situation. In case of an attack on short notice, say as a result of a meeting engagement, this subparagraph will be more brief. In case of a more elaborate attack, it might be more comprehensive, but, since an annex often is issued under such circumstances, reference to this annex obviates increasing the length of the order. This applies likewise to orders for defensive action. XVI — 2-3 ARTILLERY COMBAT ORDERS 251 (f) In case of a division order for defense, (2) of the above subparagraph might cover the placing of artillery units to carry out certain missions; such as covering the outpost, protecting a certain flank, or participating in coun- ter attacks. 3. The Field Order of the Field Artillery Brigade. — (a) This order is issued in compliance with the artillery subparagraph of the division field order. The details are worked out with full knowledge of the intentions of the divi- sion commander, ascertained through G3. The artillery fire is employed to insure the success of the division as a whole. (b) Its form is similar to that of other field orders. (See “Combat Orders” G.S.S.) Paragraph 1 generally is more copious than in the case of infantry brigades, since the artillery support must be considered from the division viewpoint, and since, to render intelligent assistance, artil- lery units must have complete information as to the plans of the infantry units to be supported. Paragraph 2 should be brief and concise. Paragraph 3 is divided into subpara- graphs — usually one for each regiment. Missions directed in the division order are allotted to proper units with more details (when necessary) than are found in the division or- der. Other missions may be added in accordance with the division commander's plan. (c) Subparagraph (x) may contain all or a part of the following : Details of movement into position. These are closely co- ordinated with the division plan in order to avoid interference and loss of time. Precautions as to concealment and secrecy. Details of firing, including adjustment, if any, preparation or counter preparation, fires to be executed during an attack, and necessary restrictions in ammunition expenditure. Instructions as to missions indicated by the air service. Restrictions as to hours of firing (on the defensive) . Use of gas and other special shell. Displacement of artillery, or, more often, warning to be prepared for rapid displacement. Such other instructions as may be necessary. (d) Paragraphs 4 and 5 are similar to those of the divi- sion order. The artillery brigade axis of signal communi- cation should be announced. The artillery regimental com- mand posts may or may not be announced, depending on « XVI— 3-4 252 TACTICS AND TECHNIQUE— ARTILLERY the situation. Their announcement tends to avoid confu- sion, but may hamper the regimental commanders, even though the locations are those recommended by them prior to issuance of the order. (e) The distribution should include the general staff, the division signal officer, and supported infantry comman- ders. 4. The Artillery Annex to the Division Order. — (a) When, in the opinion of the division commander, it is necessary to give the infantry more complete information of the artillery than can be included in the division field or- der, the artillery brigade field order may be issued as an annex to the division order. In this case, the artillery bri- gade field order will have the following additional caption : “ANNEX No— to FO No—, DIVISION ARTILLERY” (b) It is seldom necessary to issue this order as an annex. The need may arise in stabilized situations, in at- tacks from stabilization, and in defensive situations. Ordin- arily, the infantry can be given sufficient artillery informa- tion in the division field order. (c) In open warfare situations, the artillery brigade field order seldom or never is issued as an annex to the divi- sion field order. (d) Paragraphs 4 and 5 are similar to those of the division order. The artillery brigade axis of signal com- munication should be announced. The artillery regimental command posts may or may not be announced, depending on the situation. Their announcement tends to avoid con- fusion, but may hamper the regimental commanders, even though the locations are those recommended by them prior to issuance of the order.* (e) The distribution should include the general staff, the division signal officer, and supported infantry comman- ders. (f) (1) The artillery annex, when issued, has a dual function. It gives the supported troops more complete in- formation than can be found in the artillery subparagraph of the division field order, and it is a field order for the ar- tillery brigade. ARTILLERY COMBAT ORDERS 253 (2) Usually it will be more comprehensive than other artillery brigade field orders, particularly in prescribing methods of procedure; that is, in giving rules for the gui- dance of subordinate units in the accomplishment of desig- nated missions. (3) It will be issued only when the situation cannot be met through the artillery subparagraph of the division or- der and an ordinary artillery brigade field order. 5. Orders of Regiments and Subordinate Units. — (a) When time permits, regimental orders are written. When written, they are similar in form and substance, to brigade field orders. Paragraph 1 contains about the same information as is found in that paragraph of the field order of the supported unit — normally an infantry brigade. As a rule, there are battalion subparagraphs in paragraph 3. Instructions to the service battery are given in paragraph 4. (b) It often is necessary for a regimental commander to issue verbal orders, which should conform to the arrange- ment of the five-paragraph written order. (c) Battalion and battery orders may be written, but usually are not issued as formal field orders. Often they are in message form, short written instructions to subordinate commanders. When oral, the remark above as to arrange* ment applies. (d) For a more detailed discussion of the ground to be covered in battalion and regimental orders, see Chapters X and XI respectively. 6. Use of Maps and Charts. — (a) In all artillery or- ders and annexes, free use is made of explanatory maps, tracings, or charts. (b) Artillery locations or positions, schedules of fire, artillery zones, sectors of supported units, tables of displace- ment, targets, etc., can be shown more clearly on a map than by description. The written part of the order can thus be made much shorter. In case of especially important in- structions, the possibility of error is minimized by the use of both map and written instructions. (c) Whenever maps are made a part of an order, care is taken to employ an easily understood legend, and to have proper references in the written part of the order. XVII— 1-2 CHAPTER XVII Corps and Army Artillery Paragraphs Introduction 1 Unity of Fire Direction in the Combat Unit 2 The Division Artillery 3 Corps Artillery 4 Summary of Corps Artillery Missions 5 Organic Artillery of the Corps 6 Front Covered Determines Assignment : 7 Mission Determines Location of Guns 8 General Character of Corps Types of Weapons 9 Army and Corps Field Orders 10 Army Artillery 11 New Army Artillery Organization 12 Organization Into Brigades, Training, Etc. 13 Railway Artillery 14 General Scheme of Artillery Support and Assignment 15 Percentage of Guns — Division and Army 16 1. Introduction. — This chapter presents, in outline, the subject matter of Volume II of this work. The neces- sity for Corps and Army Artillery is shown by brief ex- planations of their general functions and of their relation to Division Artillery — this in preparation for the study of Larger Units. 2. Unity of Fire Direction in the ‘Combat Unit. — (a) Artillery has no independent role on the field of battle; its every mission is imposed with a view to coordinated ac- tion with one or more combat units, in which the decision accrues from the success of the infantry soldier. (b) Prior to attack, artillery preparation aims at the destruction or neutralization of the enemy’s organized de- fenses and materiel; this in order to afford such cover for infantry deployment as will render the success of the at- tack more probable. During the attack, the development of fire superiority, the intimate accompanying firing, the blind- ing of observation posts, and the neutralization of battery and machine gun emplacements, all have for their object the crushing of enemy morale and the raising of our own, the reduction of casualties in the advancing infantry, and 254 XVII— 2-4 CORPS AND ARMY ARTILLERY 255 a conservation of their means of offensive action that will permit the final stages of the action to be carried out at least on an equal footing with the opponent. (c) In defensive action, the infantry is supported by guns which are ever ready to crush an expected assault, to check an enemy’s attack or to cooperate in a counter attack for the purpose of ejecting an enemy that has penetrated our position. (d) This combined action demands cordial coopera- tion, and mutual appreciation of each others’ needs and of the fire power that can be developed by each. Above all there is need for that artillery unity of fire direction , within the combat unit, that will permit full development of fire power to neutralize the enemy wherever he impedes the in- fantry progress or imperils its security. 3. The Division Artillery. — The infantry division is the great combat unit of the combined arms. The division artillery is a component part thereof. Thus, when a division operates alone, all artillery present, assigned or attached (regardless of numbers or calibers) comes under the Division Artillery Commander, forming a single command called “Division Artillery.” Organically, the guns must be light and mobile, limited in numbers to minimum requirements, and suited to destruction of men, horses, and materiel. They should possess their own means of supply within the combat area. They must be organized for immediate fire support of designated infantry units, and for fire concentration along any portion of the division front, in accordance with the development of the action. 4. Corps Artillery. — (a) In contrast to the action of a single combat division, consider that of a corps, with two or more combat divisions cooperating in a single attack, and with other divisions in support or at rest. Each attack- ing or front line division has with it its organic artillery, re- enforced by such materiel as has become available and has been assigned to it. (b) Why, then, do we require additional fire support? There are several reasons why we require it, and why it should not, in its entirety, be assigned, even temporarily, to the several divisions. \ XVII— 4 256 TACTICS AND TECHNIQUE— ARTILLERY 1st . — In a combined attack of two or more divisions, there must be certain coordination brought about by a higher commander. The divisions are limited to designated zones of action. Questions as to targets along a common boundary must be settled, and areas may have to be neutral- ized that belong to none of the divisions engaged. In the first instance, the situation can be met by the specific as- signment of such missions to one of the divisions concerned. As for the second, the situation could best be met by a sup- erior who has the means and authority to act and is disin- terested as to the local success of any particular division ex- cept as to its influence on the general engagement. If there is considered an enemy area between the zones of two adjacent divisions engaged in cutting off a salient, or to the area between divisions engaged in a combined frontal and flank attack, the necessity for higher artillery control and assistance becomes clear. 2d . — Division artillery must possess great mobility and simple supply. Hence the missions imposed must be met by light guns of medium range, aided by the fire of howitzers upon dead spaces not covered by the flat trajectory pieces. Division artillery missions normally are limited to the areas immediately in front of the divisions, and to targets suited to projectiles of light caliber. Something must come to their aid in attacking targets beyond their reach, and in fir- ing upon protected command and observation posts, pro- tected machine gun and battery emplacements, and upon strongly defended areas and fortified points. The next higher unit, the corps, must step in and take over such missions, and hence must possess guns and howit- zers appropriate to this work. 3d . — The resistance to be encountered by a division, in its advance, cannot be judged with certainty. Sometimes the advance is checked as foreseen; at other times these checks come as a surprise. In either case, additional fire is needed. Normally, the corps artillery is called upon for this additional fire. In general, calls upon a neighboring division for this additional fire are to be avoided, as a di- minished artillery support may jeopardize its success. CORPS AND ARMY ARTILLERY 257 4th . — Likewise in defense, guns, in addition to those available in the division, may be required to check an enemy attack. If the attack be local, the artillery of adjacent units may be called upon ; but, if it be general, assistance must be sought from the corps, and the corps must be prepared for the task. 5th . — The longer stabilization exists, the stronger the defensive organization and the more essential the employ- ment of medium and heavy guns and howitzers. Such pieces form no part of the division artillery, hence the corps must come to the rescue with additional powerful assistance. While providing this means of relief, no greater aid can be afforded the division (nor can better use be made of the corps artillery) than by taking up counter battery work. This task is routine with the corps. 6th . — We have noted that, in the rolling barrage, the guns of the division support the advancing infantry to a depth of about one hundred yards. Beyond this distance, for another fifteen hundred yards or more, enemy machine guns and trench mortars can fire effectively upon the ad- vancing infantry, if seen. The duty of covering the addi- tional areas so as to neutralize such emplacements, and such enemy batteries as impede the advance of the infantry, falls upon the heavier calibers temporarily assigned the division or functioning as corps or army artillery. 5. Summary of Corps Artillery Missions. — General missions for corps artillery are — Neutralization and destruction, in areas not included in division zones but menacing the safety of advancing troops ; General fire action over areas beyond those normally assigned to the divisional artillery — say beyond 5,000 yards from the division front up to about 10,000 yards; Counter battery work; Distant interdiction and harassing fire beyond 5,000 yards from the enemy's front line to a depth of about 10,000 yards; Reinforcing the fire of division artilleries to meet tem- porarily difficult situations; Covering targets inappropriate for division artillery, on account of range or resistance ; and 258 TACTICS AND TECHNIQUE— ARTILLERY Deepening the counter preparation or the rolling bar- rage, and assisting in carrying on the latter when it passes beyond the limits of the 75s. 6. Organic Artillery of the Corps. — (a) Guns and howitzers of suitable calibers and range are required to ac- complish the missions above noted. The present organiza- tion of the corps artillery includes: 3 regiments of 155-mm. howitzers, 1 regiment of 155-mm. guns, 1 observation battalion (flash ranging), and 1 ammunition train. There is also an anti-aircraft regiment, not a part of the corps artillery (b) This artillery generally is increased by the army according to requirements, and any portion of the whole may be passed temporarily to the division to meet a special situation. 7. Front Covered Determines Assignment. — (a) It is a principle that any gups assigned to the corps, and re- tained under its control, shall be able to cover the fronts of at least two adjoining divisions. They should have a range of 10,000 to 12,000 yards to meet this requirement. (b) Within the corps zone, the corps artillery is ex- pected to reach all enemy batteries within about 10,000 •yards of our front lines. In attack, with the assistance of army artillery if necessary, it should carry on the barrage from the limit of the 75-mm. guns to the day’s final ob- jective, if within ita range. 8. Mission Determines Location of Guns. — Corps artillery guns, like those of the division, are so installed as best to carry out the missions assigned. Consequently, in defense, some are found well forward in the light gun lines, while others are *o the rear, covering the. main defen- sive position. In attack, the mass of these guns is pushed forward so as to take advantage of their long range. They are used in counter battery, in harassing and interdiction fire, and in supporting the infantry in the later stages of the attack. 9. General Character of Corps Types of Weapons. — Corps artillery consists essentially of medium and heavy XVII— 9-12 CORPS AND ARMY ARTILLERY 259 types, of which the 155-mm. gun requires some time for in- stallation. They are rather cumbersome, but comprise the lightest guns that can fulfill the required missions. As a situation stabilizes, the heavier types are brought in from the army. 8-inch and 9.2-inch howitzers, 240-mm. mortars, and additional 155-mm. guns frequently are added to the corps artillery, while the 75-mm. portee artillery, 6-inch trench mortars, and possibly some 155-mm. howitzers are passed on to the division for temporary use u 10. Army and Corps Field Orders. — Army Field Or- ders, with artillery annex, cover the following points : the assignment of general locations, target areas, and missions ; the allotment of ammunition, and provision for supply ; the apportionment of suitable army materiel to the several corps ; and the arrangements for mutual support. Likewise, the corps orders cover corresponding points for the opera- tion of corps and division artillery. (See Chapter XVI.) 11. Army Artillery. — The need for army artillery is based on the same principles of support, coordination, and supply, as indicate the need for corps artillery. Through army artillery headquarters, the action of all the artillery of the army is coordinated and controlled ; provision is made for artillery fire on targets lying without the areas of the several corps; fire is directed on targets beyond the range of the corps guns ; and, when necessary, the corps and divi- sion artilleries are reinforced by detachments from the army artillery. The organization and composition of the army artillery are outlined in paragraph 23 (c) (d) of Chapter I. 12. New Army Artillery Organization. — Organi- cally, the army artillery consists of army artillery head- quarters and an ammunition train. The anti-aircraft artil- lery of the army is not an organic part of the “army artil- lery.” The army’s needs for additional artillery are met by detachments from the GHQ Reserve Artillery. Accord- ing to the situation, GHQ Reserve Artillery, thus attached to the army, may include any or all calibers, from the 75- mm. gun to the heaviest types of railroad artillery. It is upon the latter that dependence is placed for fire beyond the range of corps guns. Guns whose range is insufficient to cover the front of more than one corps, usually do not Tunc- XVII— 12-15 260 TACTICS AND TECHNIQUE— ARTILLERY tion as army artillery but are apportioned to the several corps for service with the respective corps artilleries, or for attachment to the component divisions thereof. 13. Organization into Brigades. — Training , etc . — Army artillery may include, in addition to batteries for im- mediate service, various types held in reserve, or temporarily withdrawn from the several corps, for administration, sup- ply, and training. When practicable, all such artillery, ex- cept the portee 75s, is formed into brigades, whose organi- zation is disturbed as little as possible. Independent groups are avoided, in order to limit the number of headquarters, special staffs, and communications. 14. Railway Artillery. — The railway artillery that may be assigned to the army artillery, and generally re- tained for duty therein, comprises the following calibers now on hand: 7-inch, 8-inch, 10-inch, 12-inch, and 14-inch guns, and 12-inch mortars. Four regiments of railway ar- tillery are now organized, three of 8-inch guns, and one of 12-inch mortars, each regiment consisting of 24 pieces. Regiments of 12-inch and 14-inch rifles are intended to have but 2 rifles per battery, a total of 12 per regiment. 15. General Scheme of Artillery Support and As- signment. — (a) While there is no chain of command from the army artillery down through the corps and divisions, coordination is brought about through a strict definition of routine duties and missions. (b) Furthermore, as will be noted in “Artillery Combat Orders” (Chapter XVI) the artillery fire power of the en- tire command is regulated, developed, and controlled by each successive commander, so as to secure maximum effort and perfect coordination of the whole. (c) (1) The army artillery functions in three ways: it under- takes distant missions requiring heavy, long range weapons; it uses its fire in support of one or more of the several corps; or it is apportioned, in whole or in part, by attachment to the several corps according to their relative needs. (2) When the army artillery includes weapons whose range is too short for general army use, such weapons usually are at- tached to corps. Examples of such weapons are the motorized 75-mm. guns, 6-inch trench mortars, and the 8-inch and 9.2-inch howitzers. In like manner the corps apportions to its divisions, according to their needs, such of these weapons as are of too short range for corps use, e.g., the motorized 75-mm. guns, and the 6-inch trench mortars. XVII— 15-16 CORPS AND ARMY ARTILLERY 2GJ (d) The same general idea is carried out as to army, corps and division employment of artillery materiel of other types, that may be assigned the army from the GHQ Re- serve, or become subject to army control in particular situa- tions. 16. Percentage of Guns in a Division and in an Army. — In the present organization there are a limited number of guns organically with divisions and corps, about 5 or 6 per 1000 rifles ; but with an army, possessing its quota of GHQ reserve materiel, this number is increased three- fold, giving about the amount provided for in the major operations at Saint Mihiel, and in the Argonne during the last stages of the war. XVIII— 1 CHAPTER XVIII The Artillery Information Service Paragraphs Origin, Development and Characteristics 1 Organization 2 Sources of Information 3 Information From the Air Sevice 4 Army and Corps Artillery Information Service 5 Functions of Division Artillery Information Service 6 Regimental Artillery Information Service 7 Battalion and Battery A I S 1 8 Operations Under Varying Conditions 9 1. Origin, Development and Characteristics. — (a) The organized Artillery Information Service had its origin during The World War, when the Service des Renseigments de VArtillerie was established, early in 1916, in every army and corps artillery headquarters of the French Army. Prior to this time, information had been gathered by observation and reconnaissance conducted by the lower units — batter- ies, battalions and regiments, but very little of this infor- mation reached the higher headquarters. With the devel- opment of aerial reconnaissance, air photographs, and sound and flash ranging, the higher headquarters acquired valu- able sources of information, whereby their information be- came of as much value to the artilleryman as that obtained at the front by subordinate units. It became necessary to establish channels for disseminating this information in both directions, and systematic means for collating, record- ing, and utilizing information to a maximum advantage. (b) The Artillery Information Service was an offspring of the Intelligence Section of the General Staff. They worked hand in hand, employing both common and inde- pendent sources of information and assisting each other in every possible way. They did not become rival services, for the reason that their purposes were essentially dissimilar. The main ob- ject of the Artillery Information Service was to insure the effective accomplishment of the artillery fire missions by 262 XVIII— 1-2 ARTILLERY INFORMATION SERVICE 263 accurately locating objectives for the guns to fire on, es- pecially hostile artillery. The work of the Intelligence Sec- tion of the General Staff was “to collect, collate, and dis- seminate information of the enemy, including his organiza- tion and strength, his position, armament and equipment, his morale and habits, in order that his intentions might be foreseen and his future actions defeated ” The Artillery Information Service is concerned principally with the tech- nical information that can be utilized by the batteries while the Intelligence Section is concerned principally with infor- mation of tactical value, such as identifications, enemy strength, activity, movements, and data from which the enemy's intentions may be deduced. (c) The importance and efficiency of the Artillery In- formation Service increased with the increasing needs for accurately locating hostile batteries. Because its purpose was counter battery work, the service became highly or- ganized at the headquarters of the army and corps chief of artillery while, in the division artillery brigades, it was comparatively neglected. Later it was demonstrated that, in moving situations, the highly organized services in the higher headquarters failed to operate with the same effi- ciency as under more stabilized conditions, and that the divi- sion artillery became almost the sole source of artillery in- formation. The service now extends down to include the headquarters of battalions and even batteries. (d) In open warfare, the army and corps artillery in- formation services continued to function as best they could, digesting the information received from the division artil- lery, and from other sources, and keeping the higher com- manders fully informed as to the artillery situation of both sides. But, under conditions involving rapid movement, their information bulletins were of very limited value to the division artillery because the information therein con- tained usually was received too late to be utilized. 2. Organization. — (a) Theoretically, every individual of an artillery command is a member of the information ser- , vice, but only a limited personnel of each artillery head- quarters, as provided for by the Tables of Organization, is charged specifically with collecting, collating and dissemin- XVIII — 2-3 264 TACTICS AND TECHNIQUE— ARTILLERY ating the information gathered from all available sources. On the staff of each chief of artillery, and of the commander of each artillery unit, from the brigade down to include battalions or even batteries, there are one or more officers who have direct charge of the Artillery Information Service of the headquarters or unit to which they belong. A small enlisted personnel also is provided for clerical work and records. At the headquarters of brigades and smaller units, these officers are called Intelligence Officers. At the head- quarters of an army or corps chief of artillery they are called Artillery Information Officers. (b) Artillery liaison officers and attached personnel, on duty with infantry and cavalry units, are for the pur- pose of securing cooperation rather than information. They are not members of the Artillery Information Service of their units, but constitute one of the sources of information upon which this service relies. Organically, the artillery information service of an artillery headquarters pertains only to the staff of that headquarters and has no direct control or supervision over this service in the headquarters of subordinate units, except as may be directed by the com- manding officer of the higher unit. In practice, the artil- lery information services of the various artillery headquar- ters work in close cooperation with each other and with G2, actually operating as a centralized system. 3. Sources of Information. — With the exception of sound and flash ranging sections, the officers of the artillery information service seldom have direct control over the sources from which information is derived. The principal sources of information are: (a) Reconnaissance on the march and in moving situa- tions. (b) Artillery officers and observing parties with front line units. (It may be argued that all information required should be sent back by the infantry for general dissemination. Theoretically, this may be so, but experience has shown that the artillery must maintain its own agencies of information in the front line, and with the headquarters of infantry units.) XVIII— 3-4 ARTILLERY INFORMATION SERVICE 265 (c) Observation posts. All artillery observation posts are charged with reporting immediately all information of value, but observation posts actually constituting part of the artillery information system are limited to those es- tablished by the headquarters of battalions and higher units, and those established by flash ranging sections. (d) Air Service (balloons, airplanes, photographs) . (e) Exchange with G2, and with information services of other arms and other. artillery headquarters. (f) Radio interception. By intercepting messages from a hostile airplane to a ground receiving station, and knowing the hostile batteries pertaining to this station, our counter batteries often can be warned before the enemy opens fire, so that prompt neutralization may be effected. Applicable to periods of long stabilization. (g) (1) Shell fragments , fuses and unexploded shells. — Un- its of ail arms subject to hostile artillery fire should furnish, to the nearest artillery intelligence officer, immediate information as to the time and direction of such fire, and of the number, kind and caliber of shells falling in their vicinity. With this information, enemy batteries frequently can be connected with their habitual objectives and hence the efficiency of counter battery work in- creased. (2) When complete information cannot be supplied, frag- ments of shells and fuses should be sent to the nearest artillery intelligence officer, or a sketch of an unexploded shell made show- ing dimensions, color, markings, fuse, number and size of rota- ting bands and the number of grooves cut in them by the rifling. (3) Any unit subjected to a hostile gas bombardment should notify at once the nearest artillery headquarters, and keep, as accurately as possible, a count of the number of rounds fired. An immediate investigation by a chemical officer, or by an; artillery intelligence officer specially trained in gas employ- ment, may result in obtaining valuable technical or tactical in- formation. (h) Flash ranging (see Volume II). There is one ob- servation (flash) battalion with each army corps. (i) Sound ranging (see Volume II) . Units from GHQ reserve are attached to army artillery for installation and control. 4. Information From the Air Service. — (a) When visibility is good, and when ample protection is afforded by anti-aircraft artillery and airplanes, balloons furnish a great part of the information concerning enemy activity, such as batteries in action, circulation on roads and railroads, work- XVIII— 4-5 266 TACTICS AND TECHNIQUE— -ARTILLERY ing parties, troop movements, etc. Much of this informa- tion is phoned at once to appropriate batteries so that fire may be opened without delay on fleeting objectives or hos- tile batteries in action. Under favorable road and weather conditions, balloons may follow an advance and keep close track of the hostile artillery. In stabilized sectors, bal- loon observers submit daily reports to the corps artillery information service, which is responsible that balloon ob- servers have the necessary telephone communication for transmitting artillery information, and that they under- stand what information is desired and to whom it is to be transmitted. (b) Air photographs furnish the surest means of posi- tively identifying the locations of enemy batteries, but, in moving situations, they generally are received too late to be of value. Applications to have air photographs made are submitted to G2. Air photographs of interest to the ar- tillery may be divided into three classes : (1) Photographs of front line trenches, machine gun em- placements, observation posts, etc., including oblique photographs taken from a low altitude. These are of interest chiefly to divi- sion artillery, and are distributed to include the headquarters of regiments. (2) Photographs of the zone from immediately in rear of the first enemy position to about 5000 yards in rear of this. This zone includes most of the enemy batteries, and is of interest chiefly to the corps artillery information service. (3) Photographs of the zone in rear of (2) to include the extreme range of the army artillery’s heaviest guns. Of interest chiefly to army artillery. 5. Army and Corps Artillery Information Ser- vices. — (a) These are the information services pertaining to the artillery headquarters of the army and corps respec- tively. Their functions are generally similar. Both have artillery units to which direct information is furnished, and the reports, records, maps, charts, and office routine are substantially the same. (b) The army artillery information service consoli- dates the artillery information received from the various army corps, verifies and completes it, and disseminates this consolidated information in the form of bulletins and maps. It collects, records, and supplies information necessary to the operation of the army artillery. It sees that the artil- XVIII— 5-6 ARTILLERY INFORMATION SERVICE 267 lery information services in the subordinate units are uni- formly conducted. It exercises tactical control over the sound ranging companies, delegating the operation and utili- zation within corps zones to the respective corps artillery information services. (c) A detailed discussion of the army and corps in- formation services will be found in Volume II. (d) The usefulness of counter batteries depends largely upon the efficiency of the artillery information ser- vice, the experience and judgment of the counter battery officer, and his knowledge of the hostile batteries to be at- tacked. (e) In the army, the counter battery officer , under the army chief of artillery, directs the counter battery work of the army artillery, and also that of one corps artillery against hostile batteries in the zone of another corps. He coordinates the work of the corps counter batteries in ac- cordance with the army plan of action. (f) In neither the corps nor the army can the same officer handle both the artillery information and the counter battery work. The functions of each are too important and the time required too much for such consolidation. 6. Functions of Division Artillery Information Service. — (a) The intelligence officers of the headquarters of brigades, regiments and battalions have three distinct, but closely related functions : (1) They are agents of the artillery information service of the next higher artillery headquarters. (2) They are charged with the information service of the headquarters to which they belong, and exercise such supervision and control over the information services of subordinate units as may be directed by the commanding officer. (3) They are agents of the division G2, and bear the same relation to him as the intelligence officers of other arms. (b) The Artillery Information Service of a Divi- sion Artillery Brigade comprises the following personnel : 1 captain, 1 lieutenant, 1 warrant officer (draftsman) ; 1 corporal (clerk) and attached couriers. The duties are as follows : (1) To collect, collate and verify information from all sources available, including the study of air photographs. Though par- ticular attention is given to information of special value to the XVIII— 6 268 TACTICS AND TECHNIQUE— ARTILLERY division artillery, the information gathered must include all that is of use to any military service. (2) (a) To disseminate information, sending that origina- ting within the brigade to the corps artillery information service and division G2, and information received from all sources to the regiments of the brigade. (b) Information of particular or immediate importance is transmitted, to the units or services concerned, by telephone, radio or courier. A daily information report is rendered to the corps AIS and a copy sent to division G2. The form of this report used in The World War is inserted in this chapter. Its use is applicable primarily to periods of long stabilization. (c) GHQ, army, and. corps information bulletins, including those of the GHQ, army and corps chiefs of artillery, usually are distributed to include artillery regimental headquarters. (3) To keep the artillery brigade commander and his staff thoroughly informed on all matters of information in which they may be interested. (4) To exercise such control and supervision over the artil- lery information service in the subordinate units as may be directed by the artillery brigade commander. (5) To supervise the establishment and maintenance of bri- gade posts (brigade observation posts are generally established for the personal use of the brigade commander, especially in moving situations. They are seldom established as part of the artillery information system). A. I. S. Form 3 (c) Daily report of division A. I. O. Division F.A. Brigade Visibility: AM PM Enemy Artillery Activity Date Hour | Battery Region Cal No. of Source of Shells Information Objectives Remarks | 1 !• Total Shots: (Grouped by calibers) General Information Infantry activity: Aeronautics : Airplanes : Balloons : Movements : Troops : Trains : Works: Miscellaneous: General impressions of the day: Enemy activity: Own activity: Aeronautics : Visibility: XVIII— 6-8 ARTILLERY INFORMATION SERVICE 269 Firing of the F.A. Brigade Date Hour Battery No. of Shots Kind of Projectile Objective Observed by Effect 7. Regimental AIS. — (a) The intelligence officer at the headquarters of a division artillery regiment is a first lieutenant. He is assisted by a sergeant in the capacity of clerk. Scouts, observers and other personnel of regimental headquarters are utilized by the intelligence officer under authority of the regimental commander or adjutant. (b) The duties of the regimental intelligence officer are almost identical with those of the brigade intelligence officer, except that he is a link between the artillery informa- tion service of the battalions and that of the brigade. He sends daily to the brigade intelligence officer a written summary of information for incorporation in the report prepared for the corps artillery information service (see preceding paragraph). (c) Regimental observation posts may be established to supplement the work of the battalion observation posts in gathering information, but, more frequently, they are established for the personal use of the regimental com- mander, especially in moving situations. 8. Battalion and Battery AIS. — (a) The intelligence officer at the headquarters of a battalion is a first or second lieutenant. He has charge of the observer (or instrument) detail, and utilizes this personnel to establish and main- tain one or more observation posts. The battalion observa- tion posts are one of the main sources of information util- ized by the artillery information service. All information obtained is transmitted to the battalion liaison officers and other personnel attached to the headquarters of infantry units, to battalion scouts and reconnaissance parties, and to the batteries, including their observation posts and re- connaissance details. (b) The duties of a battalion intelligence officer are very similar to those of the brigade and regimental intel- ligence officers already discussed, except that the battalion XVIII— 8-9 270 TACTICS AND TECHNIQUE— ARTILLERY intelligence officer actually gathers a very large proportion of the information utilized by the artillery information ser- vice, while the intelligence officers of the higher headquar- ters handle the collation, verification and distribution. (c) The battery reconnaissance officers, in addition to their many other duties, are virtually (though not organi- cally) agents of the battalion intelligence officer. Batteries cannot avoid gathering a large amount of information of value to other units, as well as to the higher commanders. The importance of prompt transmittal of information, of known or possible value, should not be lost sight of by bat- tery commanders and other battery personnel. 9. Operation Under Varying Conditions. — The fore- going paragraphs are a compilation, mostly from the Regu- lations for the Artillery Information Service issued at Gen- eral Headquarters, A.E.F., France, in August, 1918. The organization and methods prescribed therein were those found to give the greatest efficiency under the conditions of position warfare. Many features of the system will break down in passing to warfare involving rapid movement. To what extent this will occur will depend on the particular situation and on the measures that are taken beforehand to meet the changed conditions. But whatever temporary in- terruption to any part of the system may be caused by rapid movements, it must be in readiness to re-establish itself as soon as conditions stabilize, even momentarily. XIX — 1-2 CHAPTER XIX Anti-Aircraft Service Paragraphs General 1 Function of Coast Artillery Corps 2 Materiel and Missions 3 Tactical Employment 4 Organization * 5 Technique 6 1. General. — (a) Troops for anti-aircraft defense are army and corps troops which function normally under in- structions and orders from headquarters higher than a divi- sion. On certain occasions, as in a march forward in the presence of the enemy, certain elements, such as the machine guns, may be attached temporarily to divisions. (b) The subject of anti-aircraft defense is treated more in detail in Volume II, Tactics and Technique, Artillery. This chapter is limited to a general discussion of the em- ployment of the elements of the defense, the subject being treated from the viewpoint of the officer, serving with a division, who finds anti-aircraft elements located and func- tioning in the division area. 2. Function of Coast Artillery Corps. — (a) The duty of providing anti-aircraft defense, in the military es- tablishment, is a function of the Coast Artillery Corps. (b) The anti-aircraft defense of the corps and the army are handled by the respective commanders of the corps regiments and army brigade of anti-aircraft troops. These officers, in addition to being tactical commanders, are heads of the anti-aircraft service at the respective head- quarters, and, as such, are staff officers of the corps and army commanders. In the accomplishment of its missions, the anti-aircraft service is more intimately related to the air service than to any other branch of the military estab- lishment. In combatting enemy air activity, its role is de- fensive, whereas that of the air service is offensive. 271 XIX— 3-4 272 TACTICS AND TECHNIQUE— ARTILLERY 3. Materiel and Missions. — (a) Anti-aircraft defense employs artillery, machine guns and searchlights. (b) Missions of anti-aircraft artillery are: (1) To prevent enemy aircraft flying at such heights over our positions that they can observe and photograph, direct artil- lery fire, attack our balloons, drop bombs with accuracy, or at- tack troops with machine guns. (2) To prevent enemy aircraft dropping bombs on vital points behind our lines. (3) To compel enemy aircraft, flying in formation, to lose their formation and thus render them more vulnerable to at- tack by our own airplanes. (4) To furnish information of enemy aerial activity. (5) While the ideal is actually to destroy enemy aircraft, the real efficacy of anti-aircraft artillery should be judged by its ability to disturb the morale of the aviator, to force him to change continuously his course and altitude, and to fly so high that he will be beyond the range of good visibility. If these aims are accomplished, it will be impossible for the enemy aviators to make accurate observations; airplanes directing artillery fire, as well as those making photographs, will work under extreme difficulties; bombing planes will be ineffective because of the great altitude at which they must fly, and hostile fighting airplanes will be prevented from carrying on their combat missions against troops, aircraft and observation balloons. (6) Since the vulnerable part of an airplane consists of less than two cubic yards, very few direct hits can be expected. There- fore, it must be the endeavor to establish a danger zone in the vicinity of the airplane. “The greatest and most effective dan- ger zone is established by using high explosive shell of the largest caliber consistent with the, necessary rapidity of fire.” (c) Missions of anti-aircraft machine guns are: (1) Defense of our front against low flying planes. (2) Close defense, particularly against - bombing of head- quarters, railheads, dumps, etc. (d) Searchlights are used for illumination of targets for artillery ground fire, and for air service pursuit. 4. Tactical Employment. — (a) The tactical employ- ment of the elements of this defense falls under two general classifications : (1) Front line defense. (2) Seacoast and back area defense. (b) The employment of the various anti-aircraft ele- ments in the front line defense are: (1) Machine guns in two lines; guns in groups of 2 or 4; not over 2000 yards between groups and lines; first line of guns within 2000 yards of our front lines. These anti-aircraft ma- chine gun* battalions should not be confused with the anti-air- craft machine gun elements of other units, such as those with field batteries or with observation balloons. XIX— 4-6 ANTI-AIRCRAFT SERVICE 273 (2) Artillery, in batteries of 4 guns each, in two lines; from 4000 to 7000 yards between batteries; first line normally about 4000 yards behind front line, but placed to protect line of resis- tance, first battle position. Batteries mutually supporting. (3) Searchlights in gun battery groups; normally four, in the form of a square not more than 3000 yards to a side; the center of the group approximately coincident with the gun bat- tery it supports. (4) Subparagraphs (1), (2), and (3) above, describe the gun area of the anti-aircraft defense, in which fire from the ground is normal. (5) In rear of the gun area, there is normally an airplane area consisting of one or more lines of searchlights (placed singly or in pairs) ; the lights, or groups, being from 2500 to 4000 yards apart in each line, and the lines from 3000 to 6000 yards apart. Pursuit and combat by the air service is normal in this area. (6) In rear of this airplane area, there may be other gun areas. The formation of a line of batteries across the armv front, in these back gun areas, usually is omitted in favor of artil- lery and machine gun defense of special localities, such as head- quarters, railheads, depots, parks and dumps. 5. Organization. — (a) The basic organization of anti- aircraft troops is the regiment, as follows : (1) Regimental headquarters and headquarters battery. (2) Service battery. (3) One gun battalion comprising a battalion headquarters and combat train, one searchlight company of 12 lights, and three batteries of 4 anti-aircraft guns each (75-mm. or greater). (4) One machine gun battalion comprising a battalion head- quarters and four companies, motorized, of 12 guns each (caliber 30 or 50). (b) One regiment is organically a part of the corps. Normally it is able to provide the gun area defense in the corps area. Also it may assist in the airplane defense, al- though the elements for this defense normally come from the army. One brigade of three regiments is organically a part of the army. Normally it is able to provide the air- plane area defense and the defense of such gun areas, in rear of corps rear boundaries, as may be necessary in the combat zone. The anti-aircraft regiments in GHQ reserve are provided in order to allow the headquarters of the the- ater of operations, or the communications zone, to under- take the defense of such rear localities as require installa- tions of a permanent nature, thus allowing the armies and corps to advance their elements as the advance progresses. 6. Technique. — (a) The normal employment of bat- teries and machine gun groups, in the defense of localities, XIX— 6 274 TACTICS AND TECHNIQUE— ARTILLERY is in triangular or ring-shaped formation about the place defended. No battery should be within 2000 yards of * place defended. (b) (1) A separate and complete communication net is neces- sary. There should be telephone service between all batteries, searchlights and observation balloons within range, battalion and higher headquarters. Batteries connect with adjacent bat- teries. Radio communication between battalions and the air service headquarters is very essential for air service coopera- tion. (2) There are three uses of this communication net: (a) usual tactical command, (b) necessity for closest cooperation of all adjacent elements, (c) lookout duties. Tactical command con- sists of assignment of targets and missions. Machine guns, for targets flying with altitude less than 1500 yards, use one round of tracer in five and one round of armor-piercing in five. Artil- lery, using shell, is employed against targets at greater alti- tudes. At night, targets are located by listening apparatus, il- luminated by searchlight, and taken under fire by artillery, and by machine guns if within range. Pursuit by air service is nor- mal in an airplane area, or, by previous agreement, in a gun area, after warnings to ground troops. Besides the above co- operation with the air service, the following signals are used; daytime by three shots in direction of hostile plane; night-time by searchlight code. (c) The following are the lookout duties: reporting all enemy air activity back through battalion headquarters to air service ; reporting night raids to army headquarters ; warning all balloons within range; cooperating with air patrol and pursuit. (d) Anti-aircraft defense is essentially to protect other ground forces from overhead reconnaissance and attack; hence its elements conform to movements and disposition of the forces. Lights and guns must be mobile. (e) For front line defense, locations are temporary, elements moving to conform to movements of army. In seacoast and back area defense, elements are permanent in comparison. Seacoast, being a first line for the country, must have elements permanently located in harbors. How- ever, elements should be as mobile in character as possible. During war, cities, industrial plants, headquarters, depots, railroad yards, regulating stations, lines of communica- tions, etc., require such permanent defense. Here captive balloons frequently are used as obstacles. XX— 1-2 CHAPTER XX Coast and Harbor Defense Paragraphs Section 1. — Introduction 1 Section II. — General Description 2-3 Section III. — Forces Employed : 4-14 Section IV. — Forms of Attack 15-23 Section V. — Submarine Mines in Relation to Coast De- fense 24-30 Section I Introduction Paragraph Introduction 1 1. Introduction. — (a) It is impracticable and un- necessary, in these schools, to take up in detail the tactics and technique of coast artillery. This is a subject for study at the Special Service School at Fort Monroe. (b) It is desirable, however, to give the other branches of the service a general outline of the work of the Coast Artillery Corps, especially in view of the new policy for the defenses of the United States, with which other branches of the service are as much concerned as is the Coast Artillery Corps. Furthermore, wherever corps and armies are organized, there will be found coast artillery troops forming an auxiliary service of some nature. Section II General Description Paragraphs General Description 2 Modifications Since World War 3 2. General Description. — (a) A distinction must be made between the terms “Coast defense” and “Harbor de- fense.” 275 XX— 2-3 276 TACTICS AND TECHNIQUE— ARTILLERY (1) Coast Defense includes dispositions and operations hav- ing for their object the meeting of hostile attack upon any por- tion of the seacoast of the continental United States, the Panama Canal, or the Insular Possessions. The elements that enter into coast defense comprise the naval forces, the harbor defense and the mobile forces of the Army. (2) Harbor Defense includes dispositions and operations for the defense of a limited portion of the sea coast, ordinarily con- fined to important harbors. Such dispositions generally include fixed armament, mobile armament, controlled submarine mines, and the troops and accessories required for their employment and local defense. The harbor defenses will be considered as units of fixed or sector artillery having a definite mission over sea and land areas, and, as such, form an important part of the sector garrison. The term coast defense is applied to the tac- tical and administrative unit comprising the Coast Artillery troops assigned to the harbor defense of a particular locality. The relation of coast defense commanders to the sector, sub- sector, and other commanders, is the same as in the case of other commanders of tactical and combatant units. (b) Our harbors, if undefended, would be the weakest 'points in our defense; since they are of the greatest value to the enemy, it is important that these points be strength- ened by more complete fortifications than other parts of the line. (c) For command and other purposes, the seacoast areas are divided into sectors, which usually include both defended and undefended areas. The limits of the differ- ent sectors are prescribed by the War Department. A de- fense sector comprises the entire sea frontier within its limit, of which the harbor defenses are strong points, not isolated points to be defended. A major sector is a sector of such magnitude as to require a sector reserve of a divi- sion or more and not susceptible of reinforcement except from the general strategical reserve or by transfer from another sector. A minor sector is a sector of such magni- tude that the sector reserve may be less than a division and yet so situated as to make it inexpedient to organize it as a subsector. A minor sector is not susceptible of reinforce- ment except from the general strategical reserve or by trans- fer from another sector. A subsector is part of a major or minor sector but forms a separate tactical command with its own reserve, under the sector command and susceptible of reinforcement from the sector reserve. 3. Modifications Since World War. — (a) The World War materially modified our ideas as to land and coast de- XX— 3 GENERAL DESCRIPTION 277 fense by the introduction and development of new means and methods of combat on sea, on land, and in the air, so that it has become necessary to revise all existing defense projects and plans. (b) Existing plans have, in general, been based upon the idea of defending important seaports, naval bases, etc., by the occupation of selected covering positions. With our present increased resources in materiel, personnel, and war experience, a more aggressive defense is warranted. (c) A properly organized system of beach defense (of favorable landing places near all vitally important ob- jects) will secure the United States against invasion from the sea, even should the command of the sea in both oceans be lost. (d) A successful invasion of the United States must be directed against certain vital areas. Defense against invasion from the sea is effective if large landing opera- tions are prevented in those seacoast sectors which cover these vital areas. (e) Within any particular seacoast sector, only a limi- ted portion of the coast is favorable for landing operations, and, among beaches favorable for landing operations, only a limited number are favorably located with reference to important military objectives. A proper system of coast defense then resolves itself into the defense, not of the en- tire coast line, but of the limited number of favorable land- ing places included in critical strategical areas. The basic idea is ; that the enemy must be denied access to any landing place upon which he could quickly establish himself in force, but it is not necessary to defend places where a landing would be so difficult that an enemy would be unable to land in sufficient strength before our reserves could be brought up in numbers adequate to dislodge him. (f) Harbor defenses (coast defense commands) are merely strong points in the line of resistance. They differ in no material respect from fortified towns along an inter- ior border. (g) Our line of defense will consist of: XX— 3-6 278 TACTICS AND TECHNIQUE— ARTILLERY (1) Harbor defense. (2) More or less highly organized beach defenses lying be- tween the harbor defenses. (3) Areas considered impracticable for enemy landings in force. These areas will be kept under observation, merely. Section III Forces Employed Paragraphs Forces Employed for the Defense 4 Naval Forces : 5 Land Forces 6 Missions 7 Armament 8 Organization 9 Projectiles 10 Trend of Development 11 Mounts and Emplacements 12 Fire Control System 13 Security and Information 14 4. Forces Employed for Defense. — In its true sense, coast defense involves the use of both naval and land forces. All branches and arms of the service have their proper function to perform in coast defense. 5. Naval Forces for Defense. — The naval forces in- clude : (a) The active fleet, whose primary function is to carry out aggressive operations with a view to destroying the enemy's fleet, thereby obtaining command of the sea. Suc- cessful action on the part of these forces would prevent any overseas operations of the hostile land forces. (b) The naval coast defense forces assigned to naval districts for the purpose of controlling the sea communica- tions therein. (c) The Marine Corps, in exceptional cases required by the national interest, may be used for coast defense, in the continental United States and insular possessions, in the way described for the army. 6. Land Forces for Defense. — The land forces in- clude: xx— 6-8 FORCES EMPLOYED 279 (a) The coast artillery troops, who are charged with the care and use of the fixed and movable elements of the seaward and landward defense of the coast fortifications, including guns, mortars, submarine mines, and torpedoes. Coast artillery troops within harbor defenses have a dual role. Their primary one is the operation of their guns against hostile ships ; the secondary one is the operation of all mobile armament and such of the fixed armament as can be brought to bear against land attacks. All coast artil- lery troops are considered available for the immediate de- fense of their individual batteries. (b) The coast artillery supports, which consist of small bodies of coast artillery or mobile troops assigned to the defense of the fortifications against attack by raiding par- ties; they are under the orders of the coast defense com- manders. (c) The beach defense, which will consist of local troops organized for initial defense of available landing places within the defense sector. (d) Divisions, corps or armies which will be concen- trated at strategic centers throughout the country, and will be available for reinforcing any beach defense which may be overcome by hostile attack. This will enable our main forces to be kept out of action until the intentions of the enemy are made known. 7. Missions of Harbor Defenses. — The missions of harbor defenses are as follows: (a) To deny the enemy possession of the position and its facilities. (b) To prevent destruction or serious injury by bom- bardment of the harbor utilities. (c) To provide an area, off the entrance, in which naval vessels and merchant shipping will be protected as far as possible against all forms of enemy attack. 8. Armament. — The armament of harbor defense areas is divided into: (a) Fixed armaments : Guns, howitzers, and mortars mounted in permanent emplacements, incapable of being moved or readily transferred, and designed to fire over xx— 8-9 280 TACTICS AND TECHNIQUE— ARTILLERY limited areas. The fixed armament is classified as major, intermediate and minor, depending on the caliber. (1) Major armament consists of 12, 14, and 16-inch guns, 16-inch howitzers, and 12-inch mortars. (2) Intermediate armament consists of 6, 8, and 10-inch guns. (3) Minor armament consists of guns of caliber less than 6-inch. (b) Mobile Armament: Guns, howitzers, and mor- tars on movable mounts, capable of being readily moved or transferred. The mobility possessed by armament of this class is limited by the type of mount, and may be class- ified as strategical and tactical mobility. For example, all types of railway armament possess strategical mobility, but the tactical mobility of certain types is limited, due to the characteristics of the mount. The mobile armament is classified as primary and secondary, depending on the cali- ber. (1) Primary armament consists of 12 and 14-inch guns, 16- inch howitzers, and 12-inch mortars on railway mounts. (2) Secondary armament consists of 7, 8, and 10-inch guns on railway mounts, and 6-inch, 155-mm. G.P.F., 8 and 9.2-inch and 240-mm. howitzers, on caterpillar mounts or tractor-drawn. (c) Anti-aircraft armament: 3 and 4.7-inch and 75- mm. guns on fixed and mobile mounts. (d) Submarine mines: Shore controlled mines, mine planters, and accessories. (e) Coast defense aircraft: Observation units, lighter and heavier than air types. (f ) Accessories : Searchlights, coast defense radio, fire- control installations, etc. 9. Organization. — The elements above indicated are organized at present as follows : (a) Gun Defense: (1) Battery commands, consisting of one or more guns, howitzers, or mortars, commanded directly by a single individual, together with all structures, equipment, and personnel necessary for their emplacement, protection, and service. (2) Fire commands consisting of two or more battery commands, the additional fire control stations and accessories and the personnel assigned thereto. The senior officer present for duty is the fire commander. (b) Mine defense: Mine commands, consisting of such XX— 9-11 FORCES EMPLOYED 281 portions of the mine defense as can be controlled advan- tageously by a single individual. The senior officer present for duty is the mine commander. (c) Fort commands, consisting of all the means of seaward and landward defense, including both personnel and materiel, located at any coast fort. Unless otherwise di- rected by the Secretary of War, the senior coast artillery officer present for duty, other than the coast defense com- mander, is the fort commander. (d) Coast defense commands, consisting of a group of fort commands provided for the defense of a harbor or point of the coast. The senior coast artillery officer pres- ent for duty is the coast defense commander. 10. Projectiles. — (a) All projectiles of 12-inch cali- ber and above, for the attack of naval targets are armor- piercing shot, designed to perforate armor at maximum oblique impact. (b) All projectiles less than 12-inch caliber, for the attack of naval targets are common steel shell with suffi- cient strength to perforate the plates of light armored vessels before bursting. 11. Trend of Development. — (a) Although seacoast forts in the United States date back to the Revolutionary War, the first coordinated study of our harbor defenses was undertaken about 1885 by the Endicott Board. The effectiveness of these defenses was limited by the caliber, range and power of existing armament. A great variety of calibers has been manufactured in the past, intended for the attack of different types of ships. In many of our important harbor defenses, there is still a large assortment of calibers, such as 3 T inch, 5-inch, 6-inch, 10-inch, and 12- inch, although the present tendency is toward the simplifi- cation of calibers. (b) The artillery has sought constantly for guns which would deliver, at the extreme range, a heavier projectile and bursting charge than could be sent by any opposing navy, and has striven to secure armament which would pierce the heaviest armor on battleships. Hence, as the capabilities of our Ordnance Department have developed, and the battle ranges have increased, together with the de- XX— 11-12 282 TACTICS AND TECHNIQUE— ARTILLERY velopment of armor and gun-power of battleships, our harbor defense guns likewise have increased in caliber and range, until we now (1922) have 16-inch guns mounted and in service. 12. Mounts and Emplacements. — (a) Practically all of the heavy guns above 6-inch caliber, mounted prior to 1917, and some of the 6-inch guns, are on disappearing carriages, using direct or indirect laying as conditions re- quire, while mortars are emplaced in pits, using indirect laying only. This mounting for guns was for the purpose of providing protection for the personnel, for, as the prob- lem was solved at that time, harbor defense batteries had to be placed so as to permit direct laying, which, of course, exposed the battery to view. (b) Another reason for mounting guns on disappear- ing carriages was that ships' guns were so mounted that, with their higher muzzle velocity and limited elevation, it was impossible to obtain a steep angle of fall, hence the shore gun crew was protected fairly well. The navy since has altered its gun mountings so as to obtain greater angles of elevation with correspondingly greater angles of fall, so the protection once afforded by these parapets no longer exists. (c) In the case of mortars, which fire at elevations of about 45° only, all the clearance necessary is overhead, thereby permitting the entire side closing of the pits. Spec- ial types of mortar emplacements are constructed where the conformation of the ground requires. In the Canal Zone, the front parapet rises nearly 200 feet above the pit floor, and at Fort Totten, N.Y., the pits are entirely en- closed and are reached by means of tunnels. (d) The type of emplacement, built for our primary armament on disappearing mounts, is not such as to per- mit all around fire, hence these guns, in most harbor de- fenses, are not suitable for fire against land targets. It is understood, however, that an emplacement for all around fire has been planned for the 16-inch gun on disappearing carriage. (e) The above limitation does not apply to mortars. Their use is contemplated in land defense plans. XX— 12-13 FORCES EMPLOYED 283 (f) (1) The disappearing carriage, before it was remodeled, permitted of the following elevations: 6-inch -5 +15°. 8-inch -5 +12°. 10-inch -5 +12°. 12-inch -5 +10°. 14-inch -5 +15°. (2) The maximum ranges with long cap projectiles were: 6-inch 14,500 yards. 8-inch 12,884 yards. * 10-inch 14,201 yards. 12-inch 13,186 yards. (3) The disappearing carriages for 12-inch guns have been remodeled so as to permit of an elevation of 15°, which gives a range of 17,300 yards. There are two types of 14-inch guns — one was 34 calibers long and the other 40 calibers long. The range of the 34-caliber gun, at 15° elevation, was 16,867 yards and of the 40-caliber gun was 19,244 yards. The disappearing carriages for these guns are being remodeled so as to permit of an elevation of 20° which will give a range of 19,700 yards for the 34-caliber gun; and 22,500 yards for the 40-caliber. There is one type of 12-inch barbette carriage which admits of an ele- vation of 35° which gives a range of 26,800 yards with a 1070- pound projectile. (g) Further modification has taken place so that the latest type, a barbette carriage, for 16-inch gun, will have 65° elevation, giving a range of 44,850 yards at an eleva- tion of 50° for a projectile weighing 2400 pounds. A table is appended showing artillery suitable for coast and harbor defense. (h) The emplacements built, pursuant to the earlier harbor defense projects, are very complete and elaborate. They include powder rooms or magazines, shell rooms, plot- ting rooms, and, in some batteries, living rooms. (i) Electrical appliances are provided, in emplace- ments of more than one story, for hoisting a projectile from the magazine floor to the loading platform of the gun. Here it is placed on a shot truck from which it can be rammed directly into the breech of a disappearing gun. With bar- bette guns, a crane with a chain hoist is provided, or some special form of loading tray from which it is loaded into the gun. .13, Fire Control System. — (a) Fire control is the exercise of those tactical functions connected with the con- centration and distribution of fire, including the assign- ment and identification of targets. XX— 13 284 TACTICS AND TECHNIQUE— ARTILLERY (b) Fire direction is the application of the methods and training necessary to secure accuracy of fire. The term “Fire direction,” as used here, is at variance with the same term as used in par. 2 of Chapter X. Here, the essence of the meaning is technique, in Chapter X, it is tactics . (c) The appliances and materiel which are intended for use ’in exercising fire control or fire direction of any unit, is called the “fire control installation” for that unit. (d) As now organized, every battery of guns above 6- inch caliber, and practically all 6-inch guns, have a separ- ate fire control installation. (e) The position finding system, which is part of these fire control installations, may be in either of two forms, the vertical base or the horizontal base. Both depend on the trigonometrical principle that knowing two angles and the included side of a triangle, all remaining elements may be computed. (f) In the vertical base system (Fig. 3) an observing instrument is placed in a tower, or as much above sea level as convenient. This distance above sea level is measured accurately. The angle made at sea level by a vertical line dropped from the center of the observing instrument is a right angle, it being assumed, for this purpose, that the sea is horizontal or level. The other angle necessary, or the one at the observing instrument, is measured by direct- ing that instrument on the target, a horizontal wire within the instrument being used for laying on the water line of the target and a similar vertical wire being directed on some prearranged aiming point such as a mast or smoke funnel. Mechanical means are incorporated in the instru- ment for correcting for changes in tide, for abnormal re- fraction, and for curvature of the earth. Having set the instrument on the target, instead of giving the measure of the angle required, the instrument is so graduated as to show directly the horizontal distance, in yards, to the tar- get, from the foot of the vertical line dropped from the cen- ter of the instrument. The instrument is likewise gradu- ated to measure horizontal angles, whereby the direction XX— 13 FORCES EMPLOYED 285 of the target from the observing station is obtained at the same time. (g) In the horizontal base system (Fig. 3), there are two observing stations in which are placed instruments for measuring horizontal angles. The distance between these two stations is known accurately. Observations on the tar- get are made simultaneously at both stations every time a bell, known as the time interval bell, strikes. The angles thus measured are telephoned to the plotting room. Here the angles, as read, are laid off on a plotting board, which reproduces, on a small scale, the base line and the lines of sight from the two observing stations. The intersection of these lines of sight then shows the position of the target. The position of the battery is also shown on the plotting board, so the direction and distance of the target from the battery can be determined. (h) Corrections in range are applied for variations in muzzle velocity, direction and velocity of the wind, varia- tion in temperature and pressure of the air from the normal, height of tide above the datum plane, variations in the weight of the projectile, travel of the target, and- arbi- trary corrections as the result of observation of fire. (i) Lateral corrections are applied for the direction and velocity of the wind, drift, travel of the target, and arbitrary corrections as the result of observation of fire. (j) These ballistic computations serve to bring the center of impact of the first group of shots as near the tar- get as can be determined without firing. This is an impor- tant factor, considering the small number of rounds avail- able and the difficulty of replenishment. (k) If the first shots do not fall near the target, the fire must be improved by corrections based on observation, until the group of shots is placed around the target. From this point on, it will be necessary to keep this fire adjusted on the target because of the constant tendency of ballistic variations to cause changes in range, and, in seacoast fir- ing, because of the constant change in range due to the movement of the target. XX— 13-15 286 TACTICS AND TECHNIQUE— ARTILLERY (l) All possible computation is made by mechanical devices so as to eliminate errors and to simplify the ob- tainment of ballistic corrections. (m) However, this does not mean that the coast ar- tilleryman is restricted to the use of these devices and cannot function without them. He is provided with com- plete range tables and is taught to use them, so that, in case of failure of his fire control system, his battery can continue to function. 14. Security and Information. — For harbor defense, the service of security is closely allied to the service of in- formation. Both are accomplished by (a) cooperation with the navy, (b) through the activities of small vessels em- ployed as scouts, and (c) through observation on the part of fort commands; the fire commands observing princi- pally toward the sea, and the support commands toward possible landward approaches. Airplanes, balloons, sea planes and scout submarines also are employed when avail- able. Section IV Forms of Attack Paragraphs Forms of Attack 15 Characteristics of Naval Targets 16 Coast Artillery Defense 17 Artillery Positions 18 Concentrations of Fire 19 Kinds of Fire 20 Tactics of Fire 21 Night Attacks 22 Heavy Artillery Available for Coast Defense 23 15. Forms of Attack. — (a) There are the following eight general forms of attack on the seacoast, each of which may be made either as unsupported or supported attacks: (1) Aircraft attacks on seaports. (2) Mine-laying attacks off the seacoast. (3) Torpedo, bombing, and gunfire attacks on vessels off the seacoast. (4) Torpedo fire into seaports. (5) Blocking attacks on seaports. XX— 15 FORCES EMPLOYED 287 (6) Bombardment of seaports by naval vessels. (7) Penetration into a harbor or water area by naval ves- sels. (8) Landing attacks. (b) Enemy aircraft attacks on our seaports can be launched either from a land base or a ship base. There are at present practically no places in the possession of a probable enemy from which hostile air raids may be launched over the ocean at our seaports. (c) Mine-laying attacks consist of laying mines for the purpose of blocking entrances to ports and even to whole sea areas. Mines are laid near the entrance to enemy ports, both with the object of closing the entrance to the port and of inflicting losses upon enemy naval vessels entering or leaving port. The following naval craft can be used to oper- ate against hostile mine layers and to clear mines from the approaches to ports : submarines, aircraft, mine layers, mine sweepers, patrol vessels, destroyers and cruisers. (d) Torpedo , bombing and gunfire attacks on vessels off the seacoast may be made by hostile submarines, air- craft carriers, destroyers, light cruisers or battle cruisers. (e) A torpedo attack may be made upon a harbor hav- ing an open and unrestricted approach and a wide straight entrance. An open roadstead is most favorable. A suc- cessful submarine torpedo attack requires a depth of 50 feet of water up to the entrance. Torpedo attacks during daylight, while possible for submarines, probably will be ineffective if proper means are taken to counter them ; dur- ing darkness, attacks by destroyers, and by submarines run- ning on the surface, are possible. (f) A blocking attack has for its object the closing of the entrance to a harbor, canal, river or water area. Only very narrow entrances can be blocked ; the operation can be carried out only under cover of darkness, which course adds to its difficulty and uncertainty. Blockships usually are es- corted by a naval force sufficient to protect them against at- tacks of the naval vessels assigned to the local defense. Di- versions may be made to distract the attention of the de- fenders. (g) Bombardment of seaports may be effected by either surface craft or submarines. A bombardment may be di- XX— 15 288 TACTICS AND TECHNIQUE— ARTILLERY rected against the defense of shore cities, utilities, bases, etc. ; against the cities, utilities and bases themselves, or against both at the same time. When bombarding land de- fenses, the hostile ships probably will close to the shortest range possible without suffering undue loss from the fire of the land artillery. When bombarding cities, bases, utili- ties, etc., such ships probably will fire from positions just within their limits of range, in order to remain at the great- est range possible from whatever land artillery may be in the locality. As a rule, bombardment of our ports, by sur- face craft, is possible only when the enemy has control of the sea; but submarines will be able to make such attacks when their own surface craft are held securely in port. Sub- marines will not attack large and important harbors where elaborate defenses have been prepared. They are limited to raids on small ports, which are usually undefended, and to exposed naval stations, such as air stations and radio stations. (h) (1) The operation of penetration into a harbor or water area by naval vessels has two general forms: (a) The forcing of a passage by main force. (b) The penetration of a passage by light craft by stealth. (2) Penetration into a harbor is a very difficult operation and seldom is attempted. The penetration of a narrow passage, such as a river or strait, offers better chances of success. (i) (1) Landing attacks may assume either of two general forms : (a) Raids by small forces for the temporary- occupa- tion of positions on shore for effecting military damage. (b) Attacks in force. (2) Raids may be carried out by landing forces formed from the crews of naval vessels, or by small detachments of troops carried on naval vessels or transports. They will take the form of sudden descents on unprotected or lightly protected areas. Coastal railways, canals, telegraph and telephone lines, shore batteries, seaplane bases, etc., are especially liable to such attacks. Secrecy and surprise are essential to success. (3) The naval operations connected with landing operations on a large scale consist of convoy duty and of covering all landing by fire. The armored ships endeavor to neutralize or destroy all land artillery that can endanger the transports, thus allowing them to approach closely to shore, so that the launches, and other small boats used in landing troops, will have only short distances to traverse in reaching the shore. The armed naval vessels at- tempt also to neutralize or destroy the land artillery, machine guns and riflemen firing on the small boats, and to support, by artillery fire, the advance of the troops that succeed in landing. XX— 16-17 FORCES EMPLOYED 289 16. Characteristics of Naval Targets. — (a) To give an idea of the distinction between capital and non- capital ships, as used in the discussion following, a brief description of these classes is given here. (1) Capital Ships Length 350 to 850 feet. Beam 70 to 100 feet. Speeds 18 to 35 knots per hour. (600 to 1200 yards per minute.) Armor 9 to 12 inches. In some cases 14 inches. Deck protection 2 to 7 inches. Primary armament 8 to 12 guns — caliber 12 to 18 inches. Maximum ranges not over 30,000 yards (mostly under 25,000 yds). Secondary armament 16 to 25 guns — caliber 5.5 to 7 inches. Maximum ranges about 15,000 yards. It is probable that, in later ships, the gun mounts will be so al- tered as to secure ranges of 35,000 yards or more. The armament of earlier ships of this class consist of: 4 guns about 12 inches in caliber. 12 to 16 guns — caliber 5 to 10 inches. Varying numbers — 3-inch. All capital ships have torpedo tubes and most of them now have anti-aircraft guns as well. (2) Non-Capital Ships These are of the greatest variety. The greater number of such ships have little or no armor, and speed of less than 25 knots per hour. These ships may be divided into armored and unarmored ships. Armored ships may have armor from 6 to 9 inches thick. Their armament may include 10-inch guns and a relatively large number of smaller guns. Destroyers are usually unarmored and carry from one to four guns of about 6-inch caliber. They may have a speed in excess of 35 knots per hour. Other unarmored ships may carry several 6-inch or smaller guns. (3) Submarines Submarines of the earlier types were limited in speed and cruis- ing radius. Guns, when mounted at all, were few and of small cali- ber. The latest submarines have a speed of about 20 knots per hour on the surface, and of about 12 knots per hour submerged. They are of large size and have a cruising radius of from 3000 to 5000 miles. They mount one or two guns, in some cases as large as 6 inches in caliber. 17. Coast Artillery Defense. — (a) The action of heavy artillery in harbor defense is essentially defensive, the mission generally being to ward off the attack. (b) This may be done either by a show of strength, in which the hostile navy suffers little or no damage or by a XX— 17-19 290 TACTICS AND TECHNIQUE— ARTILLERY decisive defeat, in which the enemy suffers heavy losses. This latter form may be considered a form of offensive-de- fense. It is secured by conducting or withholding fire in such a manner as to place the enemy in a position most fav- orable to the land guns and then carrying out a prepared plan for his destruction. (c) The choice of either of the above two forms of de- fense will depend upon the mission of the commander. If it is the prevention of the bombardment of an important city, he must take the surest effective means, whether or not he inflicts material loss upon the enemy. If his own forces are the only point of attack, he must weigh the ad- vantages and disadvantages of both methods, and the value of the results to be gained by each. 18. Artillery Positions. — (a) There are three es- sential requisites for a perfect artillery position : (1) It must permit effective fire on the enemy throughout the area in which he can maneuver. (2) It must afford concealment from the enemy. (3) It must afford material cover from the enemy’s fire. (b) The fixed armament already emplaced fulfills, in general, the first requisite and the third to a large extent. The guns are emplaced so as to permit of direct aiming; consequently, the second requisite is not fulfilled in the case of the guns, and is fulfilled to a limited extent only in the case of mortars. It will be exceptional if all three requisites exist in any one site. The cost of providing effective ma- terial cover, in many cases, is prohibitive. The natural cover afforded by different sites is one of the controlling factors in deciding upon the location of a battery. (c) The question of amount of artillery and location of batteries for coast defense is a study in itself and does not belong in this paper. 19. Concentration of Fire. — In general, the fire of land artillery should be concentrated on those elements of the enemy's navy whose missions are most imminent of ac- complishment or most effective in defeating the missions of the land artillery. Fire should not be concentrated on one element of the enemy’s forces if such concentration would leave another element free to accomplish an important mis- XX— 19-21 FORCES EMPLOYED 291 sion. The form of attack, hydrography, fleet formation, etc., also may influence the concentration of artillery fire. 20. Kinds of Fire. — Fire for seacoast guns has been classified as follows : (a) Neutralization fire against enemy vessels attempt- ing to bombard our coastal cities, bases, utilities, etc. (b) Destruction fire against all types of naval vessels, including transports. (c) Harassing fire against enemy naval craft and forces that have succeeded in seizing a harbor or landing beach. (d) Interdiction fire to prevent enemy vessels from passing certain lines at times of poor visibility. 21. Tactics of Fire. — (a) At long ranges — about 25,000 yards. (1) Enemy vessels may appear within the long range zone of our seacoast cannon for the purpose of bombarding coastal cities, bases, etc., firing at land artillery, or denying entrance or exit to our naval vessels. (2) When naval fire is directed at land artillery only, the effect will be small, due to the small target presented; and unless the enemy’s fire become too effective, it generally is advisable to reserve the fire of the land batteries. (3) When the enemy is attempting to deny entrance or exit to our naval vessels, or when the enemy is engaged in bombarding coastal cities, bases, etc., it is necessary, in the general case, to engage him in the most effective manner possible. (4) As the facilities for observation of fire probably will not permit the adjustment of each cannon separately, fire must be conducted by salvos and adjustment effected accordingly. (5) In general, no enemy vessels, other than capital ships, are engaged while at long range, as the armament they carry is of no effect against land batteries, cities or utilities at such ranges. (b) At medium ranges — 25,000 to 15,000 yards. (1) At these ranges, the enemy’s mission may be: (a) Bombardment of cities, utilities, etc., protected by the artillery. (b) Destruction of our naval vessels or hindrance of their movements. (c) Reconnaissance of our positions. (d) Attack of our artillery positions or outlying stations and accessories. (e) Removal of barriers. (2) In the case of (a), (b), or (c), the employment of the land artillery would be much the same as given under long range tactics. (3) In the case of (d) and (e), it would be best to employ only such armament as is necessary to defeat the enemy’s pur- pose. XX— 21 292 TACTICS AND TECHNIQUE— ARTILLERY (4) Practically the same system of salvo fire is employed at medium ranges as is employed at long ranges. (5) At midranges, the enemy is likely to employ his forces in two or more divisions, each with its separate mission. Under such circumstances, it is essential, generally, that each division be denied its separate mission, even though it be necessary to dis- tribute the fire of the land artillery to such extent that consider- ably less destructive fire can be brought to bear on any one tar- get. (6) In harbor defense operations, non-capital ships should not be taken under fire at medium ranges by the major or pri- mary armament unless they are armored and are carrying land- ing parties. If intermediate or secondary armament of’ sufficient power is available, that should be used. The terms “primary” and “secondary” refer to the movable armament only; the corres- ponding designations for fixed armament are “major’ and “inter- mediate.” ' (7) In coast defense operations in the intervals between for- tified harbors or other fortified areas, all armament having the necessary range should fire at transports within medium range. In such cases, it is desirable also to concentrate the fire of large groups of guns on one target to insure, in so far as possible, that at least one transport is sunk before it can get away. Both pri- mary and secondary armament should be used for this purpose. (c) At short ranges — 15,000 yards to 0. (1) At these ranges, all types of cannon would come into use, limited only by their capabilities. (2) If the targets could not, or probably would not, ap- proach closer than 10,000 yards from the fortifications, the pro- per tactics is to assign a complete fire command, or fort command, to the same target; if developments indicate that the full power and capabalities of the unit are not being utilized to advantage, then two or more targets should be attached simultaneously. (3) Within 15,000 yards, the assignment of targets by group commanders will depend upon circumstances. If the enemy must confine his maneuvers to a channel or other restricted water area, the entire fire unit should be concentrated on a single target, regardless of the range. (4) If the enemy can approach to very close range before committing himself to a restricted area, it is better, in the early stages of close combat, to designate a separate target for each battery, when group control, by fire or fort commanders, becomes impracticable. (d) (1) The principal employment of the intermediate , sec- ondary, and minor armament is in driving off destroyers, traw- lers, etc., attempting to remove mine fields and other barriers; in combatting destroyers, scouts, etc., cooperating with capital ships in an attack; in combatting attacks by destroyers and other non-capital ships; in combatting transports attempting to take aboard troops, and in destroying the small boats attempting to land troops fro mtransports. (2) In all these cases, a proper concentration of fire is es- sential. (3) At night, this armament is liable to be called upon to fire at fleeting targets illuminated for only a short time. In such cases, units larger than a battery, as a general rule, are difficult to handle, and, for this reason, fire is opened on the ini- tiative of battery commanders. FORCES EMPLOYED 293 (e) The use of interdiction fire may assume impor- tance in the future, not only to deny passage through a chan- nel or area, but to prevent raids by destroyers, on barriers, shore stations, etc. Major and primary armament, if pro- vided with instantaneous or super-quick fuses, might be used to increase the density of barrage ordinarily under- taken by secondary armament. 22. Night Attacks. — (a) Such attacks, by light craft of high speed, are to be expected. Subaqueous sound de- tectors give warning of such approach. They probably will be developed sufficiently to supply firing data. Sound rang- ing apparatus may also be in use. In either case, the data are not sufficiently accurate or continuous to justify accurate ranging, so resort is had to a large volume of fire scattered over a certain area or zone. This method of fire may be pre- arranged so that it can be brought down in the most effec- tive manner and on the shortest possible notice. (b) Searchlights are brought into action after the de- fense has been assured by other means, that the target is within searchlight range. After he is once picked up, he is at great disadvantage. Except for the use of searchlights, the same defense is employed in weather too foggy for dis- tant observation. Channel entrances or narrow points in a channel are always critical points ; hence they are kept un- der the closest possible observation. 23. Heavy Artillery Available for Coast Defense. — The following heavy artillery, suitable for firing against moving targets, is either on hand or in project for early completion and supply : Cal Type Cannon Type Mount Angles of Elevation Maximum Range Range Classification Fixed Armament (Major) 12-inch Gun Fixed — 5 to + 15 17300 Medium 12-inch Gun Fixed 0 to + 35 26800 Long 14-inch Gun — 5 to + 20 19700 Medium 14-inch Gun — 5 to + 20 22500 Medium 16-inch Gun | — 5 to + 20 23000 Medium 16-inch Gun — 5 to + 50 44850 Long 16-inch Gun — 5 to + 30 38800 Long 12-inch Mortar + 45 to -j- 65 19319 Medium 12-inch Mortar + 45 to + 65 16291 Medium 16-inch Howitzer — 5 to + 48 24940 Medium 16-inch Howitzer + 20 to -f 47 19860 Medium 16-inch Howitzer 1 + 20 to -f 48 24940 Medium Fixed Armament (Intermediate) 6-inch Gun | — 6 to + 15 14500 Short 6-inch 1 Gun 1 — 5 to + 12 13000 Short XX— 23 294 TACTICS AND TECHNIQUE— ARTILLERY Cal Type Cannon Type Mount Angles of Elevation Maximum Range Range Classification 8-inch Gun — 6 to -f 12 12900 Short 8-inch Gun 0 to + 42 23950 Medium 10-inch Gun — 5 to + 12 14200 Short 10-inch Gun 1 — 7 to + 15 16300 Medium Fixed Armament (Minor) 3-inch Gun — 10 to + 15 8950 Short Mobile Armament (Primary) 12-inch Gun Railway + 16 to + 38 27500 Long 14-inch Gun Railway 0 to + 30 30000 Long 14-inch Gun Railway 0 to + 60 41570 Long 14-inch Gun (Navy) Railway f 15 23000 Medium 12-inch Mortar Railway + 20 to + 46 9387 Short 16-inch Howitzer Railway 4- 20 to + 47 19860 Medium 16-inch Howitzer Railway + 20 to + 48 24940 Medium Mobile Armament (Secondary) 6-inch Gun Wheel car- 0 to ■+■ 38 19600 Medium riage 7-inch Gun Railway — 4 to -f 16 16500 Medium 7-inch Gun Caterpillar 0 to 16 16900 Medium 8-inch Gun Railway 0 to + 42 23950 Medium 155-mm. Gun Wheel car- 0 to -f 36 17186 Medium 155-mm. Gun riage 155-mm. Gun Caterpillar 0 to + 86 17180 Medium Wheel car- 0 to -f 42 10940 Short 8-inch Howitzer riage Wheel car- 0 to + 46 12230 Short 8-inch Howitzer riage 8-inch Howitzer Caterpillar — 0 to -f 46 12800 Short 9.2-inch Howitzer Platform -f 16 to -f 46 10060 Short 9.2-inch Howitzer Platform + 16 to -f- 46 13084 Short 240-mm. Howitzer Platform — 1 to 4- 44 14200 Short Caterpillar — 1 to -f 44 14200 Short 240-mm. Howitzer Anti-Aircraft Armament 3-inch Gun Pedestal 10000 Short 3-inch Gun Trailer 14000 Short 7 5 -mm. Gun Truck 7998 Short FORCES EMPLOYED 295 Fig. I Coast Defense Command Fort command i — r~n * I I I I I I I TT Fort command Fort command F,ANYiN& Raid (generally for capture of prisoners) 1st Stage- Genera/ shelling of trenches and area involved in the raid 7S shell and shrapnel on area to drive defenders to cover /55 he// on communicating trenches ; known occupied areas j etc and machine gun or mortar emplacements . 2nd Stage— The box made by assigned barrages , and fire for neutral izaHorr on machine gun emplacements or areas from which aftac king force mgh! be bothered . a and b - Routes followed by sub- divisions of attacking party. / - Shrapnel barrage . 2 jJTA, H ~ 7d she// barra ge . 6, 7 < 5 ? 9 t 10 ~ IS 5 neutra hzation fire on machine gun emplacements and interdiction on trenches PL ATE - XI 310 TACTICS AND TECHNIQUE— ARTILLERY Organ /z at/on of the Rolling Barrage. Accornpany/ng the Infantry in its ac/isam Showing lines in rear of wh/ oh f^v/th reference to 7H She/I fine/ the center of impact of the cat/bre noteat must not be p/ocect. As organ /zed here the fto/I/ng Barrage is genera i/y cai/ect a Dept B arrage . &Hoh//rz eh /SS Homo. SHell ftncH. Gun &/SSH shear' /r u&eo 75 SHRAP. 1 75 SHELL /ne/hytry L/he roll on- SNG RaRPASc Pl ATE-XIt APPENDIX 311 Illustrating LOCAL or PARTIAL^' Counter Preparat, on 7 7777777777 . ltl O Lf R F R O / Lear no 1 cz> Normal Barrage Possible Barrage Counter Preparation, 75 ‘s - C P from adjacent sub- sector 75s Counter Preparation !55's C. P from adjacen t sub -sector 155 's IX Counter Preparation t Corps A a ty f Put donn on/y on special reqarslj -xm Plate I. Ground Pattern of Shell Bursts A - . L LD/S TR/B U T/ON IN ROL L ING BARRAGE . ds per gun per min. borrage advancing /OO meters in 3 minuter) 3 -., hell Distribution Covering infantry on objective (1 rd per qun per min. for 30 minutes) Nod:. - Chart A illustrates the number and distribution of shell bursts assuming one battery of 75 s for all purposes per /OO meters of front - two batteries per battalion firing shell on the shell line and one firing shrapnel in advance. Arriving at an objective , chart 3 illustrates the number and distribution of the bursts if alt 75's engaged* in the barrage Ere in protective barrage for 30 minutes at the rate of t rd per gun per min. Distance 3000 meters. APPENDIX 313 p late H. Ground Pattern or Shell Burs to 50 b z;;sr ° r *t m >m >u> »»» nw m 1 Pjj _/1 /ssourt/ f^/vs^ Note Sr Ranges are estimated or taken from road niop. Ai. = Approx/ mate Sector of / st Infantry measured on the horizon . tk At many points atony river bank. At Northeast Corner of Reservoir Terrain Exercise /to, 5 (TT 3?) /S Oct /?*/. TT of Arty. Vol I . Terrain Exercise /Vo. S, 3er,es I frt3y) J IS October ^ZJ 1. There is but one light battery available from those assigned to support the advance of the infantry in this area ; it would be well to assign it to this task. It .is deemed that a sufficiently heavy concentration has been assured for the attack of hill 586, and since this light battery is not needed for the more important duty just mentioned, it finds its best use in overcoming resistance from the trenches at hill 541. 9. Trenches on hill 5U8 and hill 559 should be neutral- ized by artillery to assist the advance of the infantry. These are in the area of advance of the 4th Infantry which the 2d Battalion, 2d Field Artillery supports, and APPENDIX 357 this seems to be the best way for the artillery to give ini- tial infantry support. The real question to decide is the manner of division of the fire from this battalion. Since hill 548 is the nearer point to be taken, it is deemed best to place the heavier fire upon it in order to assist in its prompt capture which will tend to make the reduction of hill 559 an easier task. 10. As soon as the capture of the first Red line seems to he assured, artillery fire should he lifted to include tar- gets in the second Red line. The infantry carry the first line by assault and the fire of the artillery is lifted in time to safeguard them. This Red outpost line is within easy small arms range of the Red second line, and it is to be assumed that the attackers will quickly receive fire from that source. For that reason the immediate attack of the Red second line by the Blue ar- tillery is indicated at this stage. It will be noted that each of the two artillery targets described in the second line will be attacked by a battalion of light artillery, each in its own subsector. At this time the entire battalion of 155-mm. howitzers is expected to be occupied in counter battery duties. Remark It may appear that a rather heavy concentration has been ordered on the two known targets in the Red second line. Everything that can be done to lighten the infantry task is justified and expected. This amount of fire is lia- ble to become lighter at any time, due to the fact that bat- teries are sometimes interrupted in such a mission by being called upon to attack some fleeting target. For the purpose of prior coordination, it has somethimes been found useful to designate a certain battery in each battalion to be ready to respond to the duty of attacking such targets. Third Requirement: 11. To assist in repelling a counter attack, artillery must promptly abandon less important missions and con- centrate the greatest effort to crush the enemy early in this crisis . 358 TACTICS AND TECHNIQUE— ARTILLERY The first duty of an artillery commander concerned is to direct the fire of all his available weapons on the ene- my's attacking troops; his next duty is to secure artillery assistance from neighboring sources. This counter attack indicates that not only has the offensive momentarily failed, but that the enemy has util- ized his reserve energy to bring about, if possible, a local defeat for Blue. Quick response of all available forces is needed to save the situation. This is truly a crisis. The messages sent indicate the help expected. In such a case the artillery does not wait the result of the action of its own reserves ; it should be so prompt with an overwhelming fire laid on such an objective that its own reserves will not be called into action and they will be available to furnish the energy needed at a later phase. This principle is dependent on the fact that observed artillery fire can be shifted far more rapidly than troops can be moved. Swift response from all artillery available is necessary because, unless stopped quickly, the Red counter attack will, in a few minutes, be so close to the Blue lines that Blue artillery cannot be effectively used without probable injury to its own troops. Comments on Students’ Solutions 1. Indicating three areas not sufficient, they should be assigned to specific battalions. The requirement calls for the area occupied by each battalion. 2. Artillery battalions under consideration should be entirely east of Marsh Creek. See paragraph 1, Part II of approved solution. 3. Artillery positions should be selected in this situa- tion with a view to facilitating forward displacement and ammunition supply. See paragraphs 2 and 3, Part II of approved solution. 4. Positions should be in close proximity to command- ing ridges, to insure short lines of communication to good ob- servation. See paragraph 4, Part II of approved solution. 5. Areas should not be so located that any batteries could be placed on the eastern slopes of Herr Ridge. Rather close to hostile lines and unnecessarily exposed. APPENDIX 3 r >9 6. The primary role of the artillery supporting the 2d Brigade is the immediate support of the infantry advance. The principal targets at the commencement of the attack are critical points of the enemy’s first line. All 75s should be employed on these missions. 7. Under the principle enunciated in Comment 6, the maximum number of 155-mm. howitzers should fire on criti- cal points of the enemy’s first line at the commencement of the attack, using for counter battery the smallest number of howitzers consistent with an effective accomplishment of the most vital counter battery missions. 8. Counter battery missions normally should not be assigned on a time schedule, but rather for the accomplish- ment of the task to be performed; i.e., destruction or neu- tralization. 9. A counter preparation should not be employed to assist the advance of the infantry. Counter preparation is an organized defensive fire used to break up the enemy’s attack formations. It is not probable that the enemy, would, in general, concentrate his troops for defense in the identical places from which he would initiate an attack. 10. Under the conditions of Requirement 2, the number of batteries assigned to each target should be shown in the table. 11. As soon as the capture of the first Red line seems to be assured, artillery fire should be lifted to include tar- gets in the second Red line. (See par. 10, Part II, An Ap- proved Solution.) 12. Lifting the fire from hill 586 at H hour would fail to give the infantry adequate artillery support for the cap- ture of this important hill. 13. Hill 586 should receive a relatively heavy artillery concentration during the first phase of the attack. Both 75s and 155s would be desirable. (See par. 7, Part II, An Approved Solution.) 14. Fire should be directed upon definitely located hos- tile targets rather than upon indefinite areas or upon roads not known to be occupied. (See principles involved in para- graphs 8 and 9, Part II, An Approved Solution.) 360 TACTICS AND TECHNIQUE— ARTILLERY 15. Normally the fire of a 75-mm. battery should not be directed on more than one target at the same time. In this case it imposes a simultaneous double duty on the “ov- erhead,” and the number of batteries available permits com- plete units to be so assigned ; moreover, the ready flexibility for shifting fire of the 75s allows them to attack different targets successively and promptly. 16. In the counter attack, Colonel A’s orders to the 75-mm. battalion commander should indicate the target that each battalion should cover, otherwise the frontage of the Blue fire against the counter attack will not be properly ap- portioned. 17. To attempt to stop the counter attack by the fire of one battalion of 75s only is to run too great a risk by de- livering a relatively thin fire. This situation demands a sufficiently heavy initial fire to insure prompt and decisive effect. 18. The order should be issued so as to give freedom for the prompt use of observed fire which is the most effec- tive in repelling a counter attack. 19. The counter attack will probably continue its ad- vance for an appreciable period unless a heavy fire (ob- served, if possible) be put down on its front line while it is moving during the initial stage. Fire placed elsewhere, or in a fixed position, will be less effective. 20. The situation demands brief orders and messages without going into such details as prescribing rates or methods of fire. 21. Messages and orders to battalion commanders, re- lating to targets, should be framed to show the tactical mis- sion, and not merely direct a fire on a terrain feature or a line. Illustrative Problem No. 6 THE GENERAL SERVICE SCHOOLS The School of the Line 1921-1922 MAP PROBLEM No. 9— Series II (TT 91) November 22, 1921 Maps: General Map, Gettysburg-Antietam, 1 inch = 10 miles. Gettysburg-Antietam map, 1:21120; Gettysburg, Knoxlyn, Hunterstown, Arendtsville Sheets. General Situation: Blue (east of South Mountain) and Red (west) have recently declared war. The military forces of these states are mobilizing east of the Susquehanna River and west of South Mountain respectively. Special Situation (Blue) : The 1st Blue Brigade, reenforced by the 1st Field Artil- lery and 1st Battalion, 101st Field Artillery (155-mm. how- itzers), was advanced to secure and hold Gettysburg pend- ing the arrival of other Blue forces. On 14 November, 1921, this reenforced brigade encoun- tered an inferior Red force east of Gettysburg and during the following three days drove it west of Willoughby Run. On 17 November the advance of the Blue reenforced brigade was stopped on Willoughby Run by the arrival of Red reenforcements. On 17 November the indications are that the Red force, now estimated to be a division reenforced by a battalion of medium howitzers, is preparing for an attack. Strong Blue reenforcements are expected to reach Gettysburg by 3:00 PM, 18 November. On 17 November the general disposition of the Blue brigade and attached troops are as shown on the tracing at- tached; likewise all that is known of interest to the Blue SCI 362 TACTICS AND TECHNIQUE— ARTILLERY artillery concerning the enemy’s dispositions. Statements of prisoners indicate the enemy, in attacking, may be ex- pected to use the present hostile outpost line as a line of departure. The Commanding General, 1st Blue Brigade, decides to hold Gettysburg at all costs until the arrival of reenforce- ments. The 1st Battalion, 1st Field Artillery, supports the 1st Infantry, the 2d Battalion the 2d Infantry. The 1st Battal- ion, 101st Field Artillery, is held in general support of the brigade especially for the protection of both flanks in case of hostile attack. Ammunition at battery positions consists of two days’ fire. No gas ammunition available. Willoughby Run and Rock Creek are both fordable. Required : (a) Show on tracing (in blue) the targets selected for a general counter preparation to be used for protective fire when observation is not possible. (One target for each bat- tery or platoon of Blue artillery.) Also indicate by a table or other means to what battery or platoon each target is assigned. (b) Show on the same tracing (in red) the eventual targets selected for mutual support between battalions of light artillery and eventual targets for the howitzer bat- talion. Targets required are those covered by each battal- ion of light artillery and by each howitzer battery in assist- ing the local counter preparation of the other battalion (or battery) in an attack on the subsector of the latter. Indi- cate assignment of targets (by battery or platoon) as in requirement (a). (c) Show on another tracing the normal barrage line of each battery in front of the outpost line and in front of the main line of resistance. Show also the targets that the 155-mm. howitzers will fire upon should either of these bar- rages be callqd for and which will supplement them and assist in breaking up a hostile attack. *?S A pnnyi ,W/tdn r V*& i a i r.. cfe £ Legend Hostile Baiterg position determined $ Hostile Battery position doubtful- $ For other signs see pamphlet On Conventional Signs . Arrows show principal lines of fire of macht ne guns and one pounders for night defense Targets for tight mortars are shown thus ) Tatget for counter preparation are shown as follows . Normal targets ( Requirement ca)) In blue solid lines Eventual targets ( Requirement ib>) In blue broken lines Targets for normal barrage are shown as follows ( Requir ement ( Cj) In front of outpost I me Brown solid lines In front of main line of resistance Brown broken tines The general service Schools The school of the line M ap Problem No 9 Series II APPENDIX 363 NOTES 1. It will be assumed that machine guns and auxiliary infantry weapons will cover the intervals between the artillery barrage lines. 2. Barrages covering possible local attacks not required; only those to be placed on vital points in case of a general attack. An Approved Solution, Part I (see tracing) Part II This problem is intended to illustrate the employment of certain defensive fires that may be prepared for use when observed fire is not practicable, first; COP fire to be deliv- ered just prior to the hostile attack, and second; defensive barrages and accompanying concentrations to be brought down after the attack has been launched. While the de- fensive barrage has been introduced for instructional pur- poses, it must be remembered that occasions for its use will be infrequent; in the great majority of cases defensive con- centrations will be more effective. 1. When practicable, observed fire upon visible targets will always be employed in preference to prearranged fires upon probable hostile locations. However, measures must be taken to insure artillery support, no matter what conditions exist. Hence while ob- served fire will be used whenever possible, plans for other fires must be ready. This is particularly true in a defensive situation. 2. Counter battery is always important, but when the attack starts, the defenders’ greatest foe is the infantry, ivhich must be stopped. With a limited amount of artillery and a numerically superior enemy, counter preparation can be placed to great advantage on the probable hostile jump-off, and on likely assembly places in rear of same; even to the exclusion of all counter battery, which will be conducted at times of less emergency. 3. Normal missions in counter preparation and defen- sive barrages habitually will be in the sector of the sup- ported infantry. While artillery will often be able to fire promptly and efficiently into an adjacent sector, emergency fires, required 364 TACTICS AND TECHNIQUE— ARTILLERY at times of great confusion, should be made as simple in execution as possible. 4. Assignment to targets or areas to be covered by counter preparation fire are usually made by battery. Assignments may be made so that only one platoon will fire on a particular target ; this is especially true in the case of medium or heavy howitzers. The methods of attacking assigned targets, in other words the technical details of fire are left to battery commanders. 5. Sheltered areas close to lines of approach , and fa- vorable locations for the the enemy to use in initiating an ad- vance should be sought for. 6. Howitzers ( in counter preparation and defensive barrages) can best be employed in fire upon targets not suitable for 75s; such as heavy woods, ivooded hills, posi- tions behind hills, ravines or stream bottoms. 7. Habitually there will be eventual targets located in adjacent sectors or zones of action. Artillery supporting a regiment will be given eventual missions within the sectors of regiments adjacent to the one supported. 8. Eventual missions must be car ef idly coordinated with normal missions in the same zone. Not only the areas to be covered by fire of the artillery in normal support of the sector, but also the areas covered by the infantry howitzers and lanes of machine gun fire must be considered; otherwise, duplication of effort and neglect of important points are bound to occur. 9. With limited artillery support, it ivill generally be impossible to place artillery defensive fires on all probable hostile positions and works. With sufficient artillery, this would be attempted, but when the amount is limited, coun- ter preparation and defensive barrages must be placed on the most vital points, to the exclusion of others not so im- portant, or which may be assigned as eventual targets. De- fensive works, placed by an enemy to protect himself from hostile attack, will not be proper targets in this case, unless they are believed to have been selected for the hostile line of departure, or for assembly positions. APPENDIX 365 10. The 0 nailer the forces engaged , the less impor- tant and less practicable becomes fire at distant objectives. Long range counter battery and distant interdiction and harassing fire, to be freely used when large forces with ample artillery are involved, would be out of place when the decision rests with local tactical dispositions. Here all effort must be concealed to ward off the immediate dan- ger. 11. One battery of 75s can effectively cover about 200 yards in a defensive barrage. Barrage lines must be designated with this limitation in mind. Better to properly cover a few important points than to deliver an ineffective fire over a great area, or along a very long line. 12. In locating defensive barrages, the hostile prob- able plans of attack must receive careful consideration. Barrages should be laid on favorable and likely lines of approach, — the enemy must not be expected to drive against the strongest obstacles confronting him. 13. Barrages are particularly effective when they can be placed ivhere the advancing enemy will be held up. Where a natural or artificial obstacle exists, so placed that all hostile infantry cannot avoid it, his advance over such terrain naturally will be slowed up, and the opportunity to inflict severe losses correspondingly increased. The more exposed to artillery fire such ground is, the more important will be the results. 14. Advanced posts of considerable strength, if cap- tured, become positions of corresponding importance to the enemy. Hence in the defensive barrage in front of the main line of resistance, provision must be made to cover such arer*s with fire, in case they are evacuated by the defenders. 15. When an important road can be enfiladed, the op- portunity shoidd not be neglected. Machine guns will habitually cover the avenues of ap- proach; but even when they are to fire on the nearer sec- tions of roads, artillery fire may be employed to advantage at greater ranges. 366 TACTICS AND TECHNIQUE— ARTILLERY Comments on Students’ Solutions 1. There is not enough artillery available to permit counter battery during COP fire. (See Par. 2, Part II, Ap- proved Solution.) 2. See Par. 3, Part II, Approved Solution. 3. COP targets usually will be by battery for the 75s, and by battery or platoon for the howitzers. To assign more targets than this is apt to result in an ill regulated, more or less ineffective, fire. Only primary targets were called for. 4. The preponderance of COP fire, both normal and eventual, should be placed on the enemy’s probable jump-off line and forming up places. This is necessary to break up his attack. It is not considered an error to place some such fire on his main line of resistance ; but considering the lim- ited amount of artillery available, the preponderance of the COP fire should be in the vicinity of the front line as this is the critical area. (See Pars. 5 and 9, Part II, Approved So- lution.) 5. The targets for some batteries of 75s are in wooded areas. The howitzer is normally a more effective weapon for such targets. (See Par. 6, Part II, Approved Solution.) 6. The most important areas in each sector should be covered by the normal mission, the eventual missions being on the less important targets. (See Par. 7, Part II, Ap- proved Solution.) 7. The eventual mission of a battery is normally in an adjacent sector. ,It is never superimposed on its own normal mission, and in the present situation should not be superim- posed on the normal missions of other units. (See Pars. 7 and 8, Part II, Approved Solution and comment No. 8 here- with.) 8. Eventual COP fire is for the purpose of reenforcing normal COP fire; it is not fire to be used after the friendly outpost is forced back. 9. In this situation it is not advisable to place COP fire farther into the hostile rear areas than likely assembly points for regimental reserves. (See Par. 10, Part II, Ap- proved Solution.) 10. With the limited amount of artillery available, the eventual COP fire should be employed in the same general APPENDIX 367 zone as the normal COP fire it amplifies. Its purposes will be to assist in stopping a local counter attack. With suffi- cient artillery, other use might also be made of eventual COP fires. 11. Considering the amount of artillery available, an OP or CP is hardly a suitable target. 12. See Par. 10, Part II, Approved Solution. 13. Targets assigned light mortars should not also be given to artillery units. There is not enough artillery to permit such superimposing of fire. 14. See Par. 11, Part II, Approved Solution. 15. The barrage lines in front of the outpost — both 75s and 155s — should be placed close to the line to be defended. This fire is for immediate defense. 16. Barrages should not be placed so close to the friendly infantry that the latter will be apt to suffer from them. 17. Requirement C calls for each battery for a standing barrage in front of the outpost line and another in front of the main line of resistance. 18. The barrage is somewhat concentrated on the front to the exclusion of the flanks. The defensive position held by the Blues is not over-extended and hence the probabilities favor a Red envelopment as against a penetration. (See Par. 12, Part II, Approved Solution.) 19. See Par. 13, Part II, Approved Solution. 20. No coordinates or other means of orientation given on this tracing. 21. Coordinates given appear to be erroneous. 'PC; |m V ’ " 1 ’ ' ' ■ • 'V ' ' Ml ' M *$“. . ‘ V - ;.*($'■ ■ 'S h% 3s$t $fi ' ' ' ' '. ^ rift --: Vy . ' '* •*• ; . . 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