CENTRAL CIRCULATION BOOKSTACKS The person charging this material is re- sponsible for its renewal or its return to the library from which it was borrowed on or before the Latest Date stamped below. You may be charged a minimum fee of $75.00 for each lost book. Theft, mutilation, and underlining of books are reasons | for disciplinary action and may result In dismissal from the University. TO RENEW CALL TELEPHONE CENTER, 333-8400 UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN are | yg¢ IL AT U Nov 1 7 1999 IIS | When renewing by phone, write new due date below previous due date. L162 v 30 Apert YAA Aas clOVN La ACHAAM: Dy x4 TAMAR 2) AQAT Ta ARG dpe haat eae FORTIFICATION By Captain H. B. Sauerman he . ee a eet noe ‘ ensasaine a eee v pair PA, Del wu! ay, i ] ee choy Ae ne) ae ‘ n Vo SXTRACTS OF LETTERS AND R=VIEVS.. From a Golonel of Engineers U, Se Army, "I have received the advance copy of your paper on "Fortification" and have | read it with a great deal of interest, I think you have covered the subject well and I congratulate you,” eu, from an Instructor U,S,Military Acadamy at West Point, "The object which you outline in your preface has been admirably accomplished and the subject handled in a thorough, unconventional and interesting way, The cuts are excellent," From a Major of imgineers U.S,Army, "You will see from the attached that your work on “Fortification” has been of assistance to the Board of ingineer Troops, Please accept my congratulations on the result you accomplished in pusting , _this subject_in a Shape which is different from the usual text-book style and, Which ‘it strikes me, will appeal to the military student,# = Fa 2 . From a Major of Engineers U.S.Army, "The emphasis placed on concealment is not too strong, The artillery considerations are well stated, The Cavalry scope is set down simply and well, The discussion of overhead cover and splinter proofs is well done, and the information is Presh as applied to #uropean warfare," From a Major of zngineers U.S,Armny, "I congratulate you on having producec. an up-to-date treatment of the subject, The illustrations are well selected to bring out the important features." From an Officer — The Office of the Chief of Staff, "I congratulate you on what seems to me a very valuable condensation of up-to-date knowledge on the subject of fortification," From an Instructor of a Military Academy, "The advantage you take of the enormous development of trench warfare in Hurope makes your book the latest authority, besides which and most important it is written to read ~ not to solve," a ‘ — a yi Cara: 3 PREFACE Almost all military engineering work can be considered an aid to tactics. Fortification is one of the most important branches of military engineering and one of the most important aids to tactics. The civilian engineers of the nation can well take care of the con- struction, reconstruction, demolition and other engineering work in time of war, but they will not be of much help in fortification work unless they gain a knowledge of tactics. On the other hand, the militia officer with a knowledge of tactics must have some knowledge of the underlying principles of field fortification construction in order to use fortification to the fullest extent, and to the best advan- tage in solving tactical problems. The object of this short work on Fortification is: 1. To impress upon the civilian engineer and the militia officer the importance of fortification. 2. To show him how to analyze some of the problems and situations of field fortification. 3. To give him some of the main underlying principles of field fortification. 4. To create a desire for further study. 5. To show the practical application of fortification in a modern war. | The author takes this opportunity to gratefully acknowledge the able assistance, advice and encouragement that he received from Major C. W. Otwell, Corps of Engineers, U. S. A., and from Major M. J. McDonough, Corps of Engineers, U. S. A. With the instruc- tions and assistance furnished by these very able officers, many of our militia engineers have gained a knowledge which will be of great value to our nation in time of war. In conjunction with this work on fortification the author recom- mends the following publications for study: Engineer Field Manual. Field Service Regulations. Infantry Drill Regulations. Cavalry Drill Regulations. Artillery Drill Regulations. Manual for Privates of Organized Militia. Technique of Modern Tactics (Bond & McDonough). Military Engineering (Beach). : Henry B. SAUERMAN, Captain Corps of Engineers, Illinois National Guard, Member American Society of. Civil Engineers, Member Western Society of Engineers. Presented at the Western Society of Engineers’ Meeting, May 1, 1916. Modern: Trench: Warfare. 2... s.. acc. s weiss 3 tne) eee 1 Fortification.in Modern War?..2...0 45-5. 0b. 2s 2 5 Field Fortification <<: sisie's aocie si ete’y « «ao > wo no 6 The General’ Location-of Fortification’. .._.. >... 7 The Division of the Fortification Into Sectors and the Garrison for Each Sectot:),cwiacceccuie ic, eg cee rc ~ Cj = « < ~ 2 4 —— Bruel ADVANCE ‘ “1500 yos —— MODERN TRENCH WARFARE > pe i a SECTIONAL ELEVATION Fig. 1. his artillery into action to support the infantry fire. His batteries are placed in rear of crest of Red Hill so that they cannot be lo- cated from Blue Hill and opens fire on the Blue force wherever they appear in masses. When the Red artillery is put into action the commander of the Blue force brings his artillery up near the rear crest of Blue Hill and attempts to silence the artillery of the Red force by bringing his artillery fire to bear on the Red artillery. The Red artillery changes its fire and attempts to silence the artil- lery of the Blue force. Attempts are now made by both infantry forces to advance and gain ground by rushes, but they find that their losses are consider- able, as both forces bring a heavy infantry and machine gun fire on 2 any section that rises and attempts to move forward. After several unsuccessful attempts the men throw themselves on the ground and place their knapsacks or blanket rolls in front of them and continue firing. While some of the men are firing others unstrap their in- trenching tools and start digging a shallow trench, throwing the earth in front of them for protection. Each man digs for a while and then fires at the enemy while his nearest neighbor digs. Mean- while the artillery duel continues. When night and darkness come both forces work with large intrenching tools. The Red force intrenches in position “X.” They dig a firing trench and another trench 50 yards in rear of the firing trench. In this rear trench they also construct bomb proofs. The two trenches are connected by zig-zag approaches. The Blue force constructs similar trenches, but the distance between their trenches is 75 yards. In digging these trenches concealment is given the greatest consideration. The omission of the parapet entirely or very low parapets with the sod placed back on the face toward the enemy is common practice. Dummy trenches, made from the exca- vated earth, are used to deceive the enemy. When daylight comes the artillery promptly opens fire on the trenches and the infantry forces take to cover in the bomb proofs. Only a small trench guard remains in the firing trenches. The men occupy themselves during the day, strengthening and improving their respective entrenchments. The machine guns are usually placed slightly in rear of the intervals between trenches and on the flanks. They are almost always masked and under cover so as not to attract the hostile artillery fire. The second night the Blue force sends out skirmishers about 500 yards in advance of their position. The Red commander de- cides not to advance until heavy reinforcements arrive. To avoid a surprise attack he sends out small reconnoitering parties, who discover the Blue skirmishers about 300 yards from their trenches. They open fire on the skirmishers at once and are reinforced by additional men from the firing trenches. This inter- mittent fire is kept up the entire night. The Red force finds it to their advantage to advance their line 75 yards and to convert the first firing trench into a support trench with bomb-proofs, as shown at “Y.” The Red force also constructs wire entanglements in front of their position. The Blue force constructs a second line of trenches at position “B,” about 400 yards in advance of their first position. ; At daybreaek both forces start strengthening and improving their positions. Both positions are bombarded intermittently dur- ing the day. The Blue artillery brings a heavy fire on the wire entanglements of the Red force with the intention of destroying them. The Blue infantry force takes advantage of all possible means to advance their positions and, therefore, start sapping oper- - ations, which they find necessary, being in close range of the Red infantry fire. Several hours before dusk the Blue artillery opens 3 a heavy fire with high explosive shells. This fire is a steady fire directed on the Red trenches and wire entanglements. When dark- ness sets in this fire ceases. Shortly after dark the trench guards of the Red force hear noises made by the Blue force cutting the wire entanglements. ‘The Red force at once opens fire. The Blue force rushes forward with fixed bayonets. Many are shot down as they come up to the Red trenches. A portion of the Blue force finally succeeds in captur- ing a section of the Red trench, but their success is of short dura- tion. ‘The Red support is brought up and a machine gun on the flank of this captured trench brings a terrific fire into this trench. The men of the Blue force, who are not killed or wounded in this trench, escape in the darkness. Silence reigns for the rest of the night. In the morning it is found that the Blue force has con- structed another set of parallel trenches at position “C.” They have also connected these trenches to the saps which were started the preceding day by regular approaches. The artillery cannot fire on the trenches now as the two forces are too close and the danger of hitting their own forces is very great. The Blue force now starts sapping operations and continues to a short a distance from outside of the range of hand grenades and bombs. At the head of these saps small parallels are dug. The top of these parallels are covered over with logs and earth and a small steel shield with loop holes is placed in front of them. Sharp- shooters placed in these parallels act as a guard and shoot at any Red man who dares bring his head above the trenches. From these parallels the Blue force starts a tunnel, digging forward and gradually downward. This tunnel is about 4 ft. 6 in. high by 3 ft. 6 in. wide. When a depth of 15 ft. is reached the tun- nel is continued on a level. When the tunnel has passed under- neath the barbed wire entanglements, small branches are run to right and left of main tunnel. - These branches are madeugeen 6 in. by 2 ft. 6 in. The smaller the tunnel the less) noisemind the quicker completed. When under the Red trenches a large earth auger (consisting of a heavy bar and large gimlet) is used to dig holes for the mines. Melinite is then placed in these holes and the Red trench is blown. This is usually done at night. Imme- diately when the trench is blown the Blue forces rush forward, the Red forces fire illuminating shells, when the Blue force rushes into the craters made by the explosion. The Blue engineers with picks and shovels and revetment, construct a parapet and also construct approaches back to their position. The ends of crater are blocked as only part of trenches are captured. The Red force, after recovering from the shock, comes to each side of trench occupied by Blue force with the object to recapture same. They are met with a heavy rifle and machine gun fire and are © forced to withdraw. The Blue force will then attempt to capture the balance of the Red trenches by sapping and mining as described above. The Red force will countermine and endeavor to drive out ‘f the enemy and thus the struggle continues until one force or the other are practically exhausted and are driven or blown out of the trenches. The hand grenades used in this warfare consist of hollow recep- tacles filled with high explosives. There are two types: the per- cussion type, which has a fuse arranged to explode the charge when it strikes an object. The other type has a time fuse which is lighted before grenade is thrown. A small mortar is also employed, which is aimed almost straight in the air and will drop the small shell or bomb almost vertical into the enemy’s trench. For sapping the German army has now devised a digging or boring machine, with which they are able to accomplish the sapping operation in a very short space of time. Plate 2 shows a detailed sketch of the tunneling and mining operation. ‘This sketch is very clear and requires no further explanation. SAND BAGS PLAN SAND BAG METHOD DOE TAILS OF SAPPING & MINING OPERATION HB S4uerran Fig. 2. FORTIFICATION IN MODERN WAR. The extensive use of trenches and field fortification during the Russian-Japanese War and the great European War proves con- clusively that the proper and intelligent use of trenches and field fortifications, both for defensive and offensive operations, will have a most important bearing on the results of a modern battle. It may be accepted as a principle, established by experience, that a line of men can not remain stationary under fire without cover, natural or artificial. This is true in every phase of action, whether advancing, retreating, or standing on the defensive. Cover at all’times is desirable ; on the move it may be dispensed with, at a hait never. In some cases the cover will be partly natural and 5 partly artificial, i. e., partial natural cover artificially improved. In a majority of cases, however, conditions of fire efficiency and con- cealment will require a line to be placed where it could not possibly live without artificial cover. Another principle, which may be ac- cepted, is that on the offensive the line must determine the general position of the cover and not the cover the position of the line. The position of the line at any moment of a battle depends on tactical con- siderations and the progress and incidents of the fight. To prepare trenches in advance, except for defensive occupation, is to attempt to predict the future. It follows that all troops, not in a defensive attitude, must prepare their own cover after occupying a line or after they are halted. The importance is paramount of having available for instant use on every firing line the appliances and training to enable the men to get stifficient cover in the shortest possible time. This involves not alone the training of the men to dig with the tools provided, but also the knowledge and skill of their own officers to locate the trenches to the best advantage. There is no time to wait for instructions or advice from the outside. Permanent fortifications have an inestimable value as a refuge for a defeated army to rally under, as a defense to communications, as a protection to the flank of an army, as a protection of a frontier, and as a threat on the flank or rear of an advancing foe. Sea coast fortifications have a.great value in protecting sea coast cities, harbors, naval bases and other strategic points along the sea coast. FIELD FORTIFICATION. Field fortification is an aid to tactics and it should be con- stantly borne in mind that fortifications are designed for tactics, not tactics for fortifications. A thorough study of the general tactical situation is the first and most important step toward a successful application of fortification. The following questions will arise in the study of the situation: 1. What is the general plan of operation? 2. What part are the fortifications to take in the general plan of operation ? 3. Will the fortification be used for defensive operation only? 4. Will the fortification be used for offensive operation only ? 5. Will the fortification be used for combined offensive and defensive operations? 6. What will be the strength of the attack infantry, cavalry and artillery? 7. What light arms, equipment, machine guns and artillery will probably be ‘used by the. enemy ¢ 8. From what direction is the attack expected? 9. At what time is the attack expected? : 10. What are the natural features of the ground at- place where attack will take place? 11. What is the available armament and available strength of garrison for the fortification? 12. What are the available lines of retreat to a new position should the enemy’s attack be successful? It will not be possible to obtain all of the information as out- lined above. Information relative to the strength and armament of the enemy, time and place of attack, etc., will in many cases be very vague and unreliable. All available means must be used to secure as much information and as reliable information as can pos- sibly be secured. ‘The time for securing information will usually be very short, and for this reason the judgment and reasoning power of the officer must be used to the fullest extent in determining many facts. The work of Field Fortification may be divided as follows: 1. The general location of the fortification. 2. he division of the fortification into sectors and the garri- son for each sector. 3. The division and disposition of the support and reserve. 4. The machine guns and their disposition. 5. The artillery position. 6. The disposition of the cavalry. 7. The trench'trace and profile. 8. The overhead cover. 9. Loop holes. mi. Drainage, 11. Artificial concealment. 12. Clearing the ground. 13. Obstacles. 14. Dummy trenches. 15. Execution of work. 16. Observation, telephone and water supply. THE GENERAL LOCATION OF FORTIFICATION. The requirements of a well fortified position are: Concealment. Good field of fire. Natural or artificial cover. Obstacles for retarding’ or directing the course of enemy. Easy and concealed communications for tactical move- ments of your troops. 6. Obstructed and unprotected communications for enemy. 7. Easy digging soil; free from rocks and roots. 8. Sufficient height to give good view over ground over which enemy will advance. 9. Nattiral flank protection. | Concealment is of the greatest importance. This does not only include the trench and parapet, but also the obstacles in front of same, for if these are not concealed they will assist the enemy in 7 ae taal a locating the trenches in rear and the hostile artillery will further destroy same. Formerly the field of fire was given the greatest con- sideration. The war of today has demonstrated that a field of fire of 100 yards will be sufficient if it can not be extended without loss of concealment. Low parapets, the omission of parapets, a back- ground, avoidance of sky-lines, narrow trenches, covered trenches, rounded crests and corners and the concealment of disturbed soil are all very effective in securing concealment. For concealment against observation from aeroplanes and also horizontal concealment, the author suggests a canvas covered trench. The canvas can be painted any color to suit the surroundings, or by | ress CANVAS COVERED POUBLE NER FikinG TRENCH : ay FuRiInG TRENCH Kige 3) scattering lightly grass, earth or other matter over the canvas almost perfect concealment can be obtained within a short space of time. The canvas covering will further protect the garrison from rain and the direct rays of the sun. Figure 1 on Plate 3 shows an ordinary firing trench provided with the canvas cover, as suggested by the author. Figure 2 shows a double tier firing trench provided with this same covering. ) The field of fire must permit of the full use of the defenders’ weapons. This requires a level or slightly sloping open space in front of the trenches for 100 to 700 yards. A grazing or parallel to the ground fire is the most effective. Fire delivered at a consider- able angle with the line of trench is not very accurate. The limiting angle for good results is about 12 degrees. Trenches should, there- fore, be fairly straight and at right angles to the fire. Cover, either natural or artificial, is essential for the protection against infantry or artillery fire. Natural cover is usually obtained behind crests of hills, in ravines, dry river beds, etc. Artificial cover is usually obtained in sunken roads, behind road and railroad embankments and in dry ditches or special trenches. Obstacles for obstructing or directing the course of the enemy consist of marshes, rivers, valleys, cliffs, hedges and forests with heavy undergrowth. All these natural obstacles may force the enemy to attack only from one line and direction. ‘The defender will then have the advantage to concentrate his entire force and means at the point of attack and prepare the position in advance. Where the enemy can be forced to attack over a narrow well swept front, the attack (everything else being equal) is almost certain to fail. Easy and concealed communications can be obtained behind rising ground, through woods, through ravines, through large stand- ing corn, etc. High sites furnish better protection for communicat- ing trenches than do low sites, but this advantage of the high site is oft’times offset when the defenders are compelled to deliver an in- effectual plunging fire. Where natural concealment for communi- cations can not be obtained artificial zig-zag or traversed com- municating trenches must be built. Cover trenches for supports and reserves must be constructed in locations where the country is flat. Where it is possible, the enemy should be forced to attack over difficult ground, requiring crossing of streams, etc., and where he will be exposed as much as possible, where his fire can not be devel- oped and where his movements will be impeded. Easy digging soil, free from large stones and roots, is very desirable where the time is very limited for the construction of trenches. Authorities differ regarding the height of a position. It is desirable to have a certain‘ amount of command for a defensive position. This height need only be sufficient to give an unob- structed view over the ground in front. In flat open country this height may be very little. The slopes to the front should be gentle and evenly sloping. A strong defensive position is one where one or both flanks are protected against attack by natural or artificial obstacles—rivers, deep marshes, mountains, etc., form good natural obstacles for protection. It is very apparent that very rarely a position will be found which will meet all of the conditions and requirements as outlined, 9 but it is also very evident that the position which meets most of the conditions and requirements will be the most easy to defend. ‘The officer, should, therefore, carefully study his position accordingly, for upon the selection of the position may depend the results of the battle. THE DIVISION OF THE FORTIFICATION INTO SECTORS AND “PRE GARRISON FOR EACH SECTOR. Field fortification, for tactical and administrative reasons, - should be divided into independent sections of such size as can be well commanded by one man. Such a division is an aid to tactics in that it allows the tactical units with their supports, reserves, supply, etc., to be kept together, and the duty and responsibility of attending to the many details can easily be divided by the commander among the subordinate officers. It is very apparent that a better field control will result with such an arrangement, and it is also very evident that such a division will Stehon FirinG& TRENCHES (TAG eee SUPPORT, gums 2 STEN K=Kir CHEN eas TA THE REGIMENTAL we WATER UNDER ENTRENCHMENT R.Br =DRESAiNa STATION COVER | MG=MACHINE Gun eee RESERVE CAPT H® SALERMAN Fig. 4. aid the administration and supply department in the same manner. To illustrate the arrangement of a modern field fortification sector, Plate 4 has been prepared. Briefly, the arrangement, as outlined, is as follows: Firing trenches are designed for full company units. A small trench guard is always stationed in the firing trenches. This may consist of one platoon or less in case of artillery bombardment. In case of threatened infantry attack the other platoons of each company which are stationed in the bomb-proofs are rushed for- ward through the communicating trenches and take their plane in the firing trench. When the entire first battalion is in the firing trench, the second battalion moves up into the support trench and in the bomb- proofs. These bomb-proofs are loop-holed to permit of firing to the front and flanks. In case of capture of the first firing trench, the first battalion will fall back to the support trench and there combine 10 with the second battalion to stop the enemy’s advance ; under normal conditions the second and third battallions remain under natural or artificial cover and occupy the trenches only when conditions re- quire it. When conditions require it the arrangement can be modi- fied so that two battalions can be placed in the firing trenches with only one battalion in reserve. The machine guns are placed ap- proximately as shown. In this location—they are in position to deliver a fire between the intervals of the firing trenches and they can also be rushed forward to deliver a flanking fire attack on the firing trench in case it is captured and occupied by the enemy. The machine guns can also be placed so as to protect the flanks of the outer firing trenches. All machine guns should be masked or con- cealed so as not to attract the hostile artillery fire. THE DIVISION AND DISPOSITION OF THE SUPPORT AND THE RESERVE. Major W. W. Harts, in his excellent work, “Notes on Field Fortification,’ in the Professional Memoirs, gives the following information regarding the garrison, support and reserve: “From one-quarter to one-half of the entire force should con- stitute the general reserve and the remainder be distributed in the various sections of the front as needed. In each section it is advo- cated that about one-quarter to one-half of the force assigned to it should constitute the section reserve, ‘and of. the troops remaining about one-half or two-thirds should be supports. About one-fourth to one-sixth only of the section’s force will actually be in the trenches before being attacked. It seems to be desirable to reduce the force of men actually in the trenches to the smallest number consistent with safety. No exact proportion of reserves and sup- ports can be given for all cases and the foregoing is only stated as a guide in forming one’s own decision, which must always depend on the conditions peculiar to the ground, including the shape of the front, whether straight or curved, the size of the garrison, the enter- prise of the enemy and the interior communications. “But room in the trenches must usually be made for all the troops in the section, including perhaps space for some of the gen- eral reserve, so there must be some calculation made as to how much trench must be built or how much front can be occupied. “Trenches must always be able to furnish enough aimed rifle fire to stop any ordinary infantry attack across the open space in front. It is plain that this will vary greatly in different terrain. One might suppose that the enormously increased power and rate of fire of the modern rifles had lessened the number of rifles neces- sary, and that the old rule of thumb of one man per pace of firing line is no longer required. Such density is no longer necessary, except perhaps for a short time for repelling assaults after the attacking troops have managed to bring a large force within close assaulting distance. At such times the maximum amount of fire possible is needed. Men can not use their rifles accurately if occupy- ing less space than one pace of the front. This may then be adopted as a maximum density required for any part of the front where a 11 close attack may be delivered. This assumes that a part of the general reserve is on the line. At other places less hard pressed more length of trench and less density will be possible. An English authority has even stated that one man to every eight or ten paces is enough to check any infantry assault on a well chosen position, or including reserves and supports from two to five paces per man. We may safely conclude that from 1 to 4 yards per man, including sectional reserves and supports, are limiting estimates depending largely on the ground. The density suggested in our field service regulations, including supports and local reserves, is one man per yard, giving a front of 750 yards for the battalion, including inter- vals of 100 yards between companies, 1,500 for the regiment, and 4,500 for the brigade. The judgment of the officer as to the strength required will have to be exercised in each of the larger parts of the line in order to have it fairly balanced, increasing the density in some places and decreasing it in others.” THE MACHINE GUNS AND THEIR DISPOSITION. Machine guns are now recognized as one of the most potent factors in battlefield operations. Our Field Service Regulations, 1914, Par. 34, gives us the following information: “Machine guns are emergency weapons. ‘They are best used when their fire is in'the nature of a surprise to the enemy at the crises of combat. Their effective use will be for short periods of time—at most but a few minutes—until silenced by the enemy. When engaged they must be used to the limit of their effective capacity. On the offensive they find their use in assisting the attack to obtain fire superiority temporarily lost and against lines of trenches which are to be assaulted. In the defensive they are used against large targets visible for a short time only, and on advancing lines of the enemy’s infantry within the short and mid ranges. The effect of the enemy’s fire, particularly his artillery fire, on machine vuns, is lessened by their employment in small groups.” In event of an assault they enable a heavy fire to be developed at a point where the enemy is strongest, provided the machine guns are placed so as to admit of their free use. For the defense of flanks of both infantry and artillery, for the defense of ditches, for positions where infantry would be visible or liable to enfilade fire, the machine gun posted behind natural cover or other concealment will give excellent service. Machine guns are placed between in- tervals of trenches as shown in Plate 4 and also on the flanks of infantry and artillery positions. They should be well concealed and the emplacement so constructed as to afford a maximum pro- tection to the gun detachment consistent with the free use of the weapon. Splinter-proof overhead cover is desirable and should be provided wherever possible. Shelter should.be provided for both gun and detachment when not engaged. It will sometimes be found to advantage to connect emplacements by communicating trenches. 12 Fig. 1, Plate 5, shows a Single Machine Gun Emplacement. Fig. 2 shows a Double Machine Gun Emplacement. Lieutenant Henry J. Reilly gives the following report regarding the value of machine guns in the present European war: It is particularly in the defense of an intrenched position that machine guns are useful. Here, as in a fight in the open field, they must not open fire too soon, or the hostile artillery will wipe them out. Therefore, they generally remain silent until the enemy’s infantry comes out of its trenches and starts across the intervening space in its endeavor to capture its opponents’ trenches. Then the machine guns open fire and keep it up until the last of the enemy left alive or unwounded have run back into their own trench or until captured or put out of action by a hand grenade if the attack is a success. The Germans frequently arrange their trenches so that if occupied by the enemy a machine gun can fire down them, thus enfilading him and driving him out. If the configuration of the ES ‘oe 184 -40 ‘ SECTION C-O “L See SECTION A-B s., bed Ont =3'0 SECTION A-B SECTION A-B SECTION C-D EMPLACEMENT FOR EMPLACEMENT FOR GUN Pit i! 2-MACHINE GUNS TOTAL EXCAVATION $30 CUFT : MACHINE GUN TIME TO CONSTRUCT SEMEN 2TOGHRS TIME To CONSTRUCT I2MEN 1-2HRS *. Fia.l Frie.2 Fia.3 . igi ay ground will permit it, they place most of their machine guns, not in the first line of trench, but in some position back of it. This is done to avoid probable destruction by the heavy shelling to which a trench is subjected by the enemy’s artillery before an attack is made. 3 In accordance with this principle, where the Germans have been able to prepare a position ahead of time, they pick out a gentle slope and put three lines of trenches on it. The machine guns are placed in the last line, thus being able to shoot not only over the first two lines at any approaching enemy, but making a strong third line very difficult to capture, even though the first two lines are captured. Also until this third line is captured and a hole thus broken entirely through the position, little is gained by the capture of the first two lines. Frequently in Poland there have been large stretches of country where the invaders have had no other desire than to remain on the defensive. In these stretches the Germans strongly intrenched and 13 garrisoned the important points. Between these points they con- structed several lines of trenches, each with a very wide barb wire entanglement in front. These trenches would have comparatively few troops in them, but a considerable number of machine guns. While a Russian attack might succeed in breaking through most of the entanglements in spite of the machine gun fire, it would take them so long that the German reserves from central points in the rear of the line would have ample time to get up. THE ARTILLERY POSITION. The artillery position is usually selected by the chief artillery officer after he learns the general situation and requirements from the commander. Artillery positions are generally in rear of the intrenched — infantry positions and are concealed from view usually by natural cover. When conditions permit, the artillery should be placed in a somewhat commanding position. Due to the perfection in firing by indirect laying, guns are now usually placed in rear of the crest of the hills. The advantage of such a position is easy concealment and easy concealed withdrawal, both of which are more important than direct fire. Concealment and mobility are in fact the most important factors. Dispersion is very necessary to reduce the hits of the hostile artillery, and with the improved field telephone sys- tem, guns can be scattered over a wide area without the loss of control. There should be numerous alternate emplacements, with casemates for the protection of the men. This will allow changes of position with a minimum loss of time. Positions should be selected to furnish a concentrated cross fire on all possible lines of advance of the enemy. Whether the heavy guns should be placed to the front or to the rear depends very much upon the enemy’s armament; if he has only the small caliber guns, the large guns may be kept in the rear; if the enemy has large caliber guns it will be necessary to place the heavy guns to the front to prevent him from building his batteries. Good sites for observation stations are a prime necessity.” They should be well concealed and connected by telephone to the different battery commander stations. Where it is possible, emplacements should be connected by concealed approaches. The light field guns, which in practically all armies are about - three-inch, are generally found in the zone from 2,000 to 4,000 yards from the enemy’s trenches. The heaviest guns, such as the 305 millimeter (about twelve-inch) howitzer, are found at from 6,000 to 8,000, or even more, yards from the enemy’s trenches. The guns of the intermediate caliber, such as ten-inch howitzers and fifteen centimeter-rifles, are found somewhere between the light field guns and the heaviest ones. The Austro-Hungarian 305-millimeter howitzer has been ex- tremely efficient thorughout the war. A large part of the work | 14 credited by the allies to the 420 millimeter has in reality been done by the 305. One of the marked features of this gun is its mobility. The gun, the carriage in two parts, and a steel platform on which the gun and carriage rest during firing, travel on four steel trucks with heavy wheels, which are pulled by one or more traction engines, depending upon the state of the roads. When the firing position is reached, the ground is leveled, the steel platform put down, and the gun and carriage mounted on it. The 3-inch field gun, the 6-inch long range heavy guns and the 5-inch howitzer and mortar are usually employed in the field fortifi- cation. The mortars and howitzers are usually located in retired posi- tion on the reverse side of hills, in ravines, etc. In addition to the heavier guns, the 1-pound automatic and the 3-pounder and 6-pounder rapid fire guns are employed to good FIELD HOWITZER Of @iEGE GYR «| q Y . ew , ‘ : : \ Winn, BAZ edt] H af vc H en’ pe aie } 0) Eye _ the — —Uet ALF on - Je INFANTRY TRENCHES wir EN TAN@LEMENT REAR ELEVATION FORTIFIED ARTILLERY POSITION Fig. 6. advantage. In case of assault they will bring a heavy fire to bear on the enemy. Fig. 3, Plate 5, shows a very simple and easily constructed gun pit. The pit can easily be modified to meet different conditions and the low parapet admits of easy concealment. It was used extensively by the Russians in the Japanese War. Plate No. 6 shows a fortified artillery position on the front slope of a hill. Such a position ds a difficult one to conceal and further makes it very difficult to change position without being observed by the enemy. Brush, canvas, trees, sunken roads and dry ditches will oft’times help to overcome these disadvantages. It will be noted that the guns shown in this plate are all firing over the infantry trenches. This is a very common practice in the present 15 European War. ‘The guns should be placed at least 600 yards in rear of the infantry position so as to protect the artillery position from flank and rear attacks and further not expose the infantry to loss from premature bursts. For the sake of showing the gun posi- tions clearly, they are all shown in cross section. In actual practice these guns would not be placed one directly in rear of the other, but would be widely scattered. THE DISPOSITION OF THE CAVALRY. Cavalry can render valuable service in connection with field fortification by the performance of the following duties: 1. Reconnoitering the enemy’s position and securing informa- tion as to his strength, armament, disposition of troops, etc. 2. Delaying the enemy’s advance so as to give the troops sufficient time to dig their trenches. 3. Selecting and holding strong defensive positions in advance of the infantry. 4. Protecting the flanks of a fortified position. 5. Threatening the flanks of the enemy and forcing him to attack along certain lines. 6. Clearing the ground by tramping down crops, such as standing corn, etc. 7. Performing demolition work. Cavalry in modern war will seldom be called upon to make mounted charges. It has the great advantage of mobility. Infantry carried by motor trucks does not have the mobility that cavalry has, because the trucks are confined to good roads and also on account of the small number of trucks available. The cavalry in the present European War is mostly employed in seizing strong position in advance of the infantry and holding these position by fighting dismounted until the infantry arrives. When the Allies were trying to extend their lines to Antwerp and the Germans were trying to reach the Belgian coast in October, 1914, the cavalry of both armies played a most important part in the region of Lille and Ypres. Cavalry played a most important part in the Allies’ retreat and the German’s advance to the Marne. , Cavalry is also employed in filling gaps between infantry units. Owing to its great mobility, it can reach decisive points long before it would be possible for infantry to do so. The present war shows many instances in which cavalry filled important gaps. THE TRENCH TRACE AND PROFILE. Prepared fortified lines of resistance will consist normally of successive lines of trenches or supporting points with intervals, the intervals being such that mutual defense by cross fires and flanking fires is assured. The supporting points will usually be groups of rifle trenches combined with natural topographical features. The 16 intervals between trenches and Eee eaue points will vary from 100 to 800 yards. The flanks of a trench or a position will always be tempting points for the enemy’s attacks and they should therefore be secured by resting them on impassable obstacles or, if this cannot be done, by echeloning them to the rear and placing reserve trenches close at hand. Long trenches are not desirable even where the ground permits of their application, which it ordinarily does not. Any long trench once located by the enemy easily leads to the disclosure of the remainder. A long trench penetrated at any point will generally become untenable. For these reasons it is considered preferable to limit the length of a single trench to that required for a company and if a greater development of fire is needed, additional trenches of company, platoon or even squad length may be constructed. The several trenches of a group need not and generally would not be on the one line, but might by separated in depth as well as laterally. The trace of a trench should follow a contour. Men standing about 11 paces apart may hold a tracing tape at the height of parapet. By looking all along the tape, it will be seen whether each part of the parapet will command the ground in front of it. If the command is greater than required, the parapet may be lowered or retired. Note also whether the longest trenches are on the sides of the easiest approach, if not trace must be modified. Fairly straight lines at right angles to the delivery of fire are to be pre- ferred. If curves must be introduced they should have a radius of at least 20 yards. All trenches should be long enough to give an effective volume of fire. A squad trench 11 paces or 9 yards is about the minimum. Tracing and profiling are not independent operations. The trace depends upon the profile and the profile upon the trace. The profile, however, is fairly well standardized while the trace must be determined by the circumstances and conditions. In field fortifi- cation the term trace usually designates the horizontal projection of the interior crest. This trace, as stated before, should follow a contour; if the contour curves, the trace should also curve; sharp angles should be rounded off so as to make them less conspicuous. Plate No. 7 shows a trace of a Battalion Supporting Point in accord- ance with the German Regulations 1910. Due to the improvements in rifle and artillery fire, the high parapets and broad trenches of the past years have been replaced with narrow trenches with very low parapets or with parapets entirely omitted. If a parapet is used, the crest should not be over 18 inches above the ground and the surface should be a straight gentle slope, not steeper than 1 on 6. Both these conditions help considerably toward concealment. The front wall should be as near vertical as possible; this provides better shelter and helps the soldier when in firing position. An elbow rest of 9 to 12 inches is also an aid. Most authorities state that a height of 4 ft. 3 in. to 4 ft. 6 in. from the bottom of the trench to the crest of parapet is 17 necessary for a man firing while standing. The author’s experience has been that 4 ft. 8 in. will better meet the average condition on account of the dirt along parapet being disturbed by movement of rifles, etc. Furthermore, in case of heavy rains the height of parapet will be reduced. Should this height be too great for certain soldiers it can readily be decreased by throwing a little of the dirt to one side. There is a practical limit to the narrowness of a trench. A trench narrower than 2 ft. can not be dug and used to good advan- tage. It is too narrow for two men to pass in it or for a man to sit with his back to the front wall; 3 ft. is the limit for this purpose. Major Harts gives the following essentials of the profile: First, a low bullet-proof parapet not over 18 inches high with a single gentle slope not steeper than 1 on 6 and an elbow rest 9 inches below the crest; second, a narrow trench with vertical or nearly vertical sides and of sufficient height to cover a man standing, is Ot ——__* TYPE © IDEAL BATTALION SUPPORTING PoinT. GERMAN REGULATIONS 1910 APLATOONS IN TRENCHES bg * SUPPORT 2 COMPANIES IN RESERVE TRENCH ROOM FOR ENTIRE BATTALION lYo FER MAN ABou T 400 YHDS LONG OVERHEARD COVER FoR 2 PLATOONS. Big. and wide enough to sit in and permit another to pass; third, some protection from enfilade or oblique fire by using traverses or special arrangement of the ground plan, and fourth, a bottom slope with a gutter for drainage. The following tables and information relative to range and penetration will assist in determining the necessary thickness of parapet: RANGE. Field Heavy Bales Rifle Artillery Artillery Yards Yards Yards Distantiine eee Over 2,000 Over 4,500 Over 6,500 Tgviovusts omen 2.000 to 1,200 4,500 to 3,500 6,000 to 5,000 Biectiverio maces 1,200 to 600 3,500 to 2,500 4,000 to 2,500 Closew.. Wether an Under 600 Under 2,500 Under 2,500 18 PENETRATION OF RIFLE BULLET. ee Inches 200 Yards ~ 600 Yards Rammercial Steel...........0....005 0.30 0.20 One-inch broken stone, gravel....... 4.80 4,28 Hard coal between 1-inch boards.... 9.00 7.00 fericeemasonry; cement™............. 2.20 1.16 Brcko masonry, lime*?....2..,...... 2.40 1.14 EEN so ees ake et, We, 18.18 11.96 Mamcrete, port, 1-3-5..0% wel. 2... ee. 3.00 1.86 ASE ERE eae, ce een ae 26.46 12.46 MIRE eg Sieagtth Dkls oss dos 30.00 13.00 EI MR ey rn ie ita ts nie 25.72 13.00 IITA TIT: 6 Sasso caida ee oe do's a, 30.00 16.12 ES cs ee re ee 60.00 32.00 EFFECT OF ARTILLERY, FIRE, Up to 3,000 yards, the 3-inch field gun, using high explosive shell, is effective against ordinary types of overhead cover for field trenches, brick buildings and stone walls 2 feet thick. It is ineffective against earthen parapets. The heavier. types of field guns and howitzers are effective against all kinds of field works, and protection against this kind of fire must be secured by concealment. iene, : =F | d gy uy “A ar Fk eto | - Wo rs + dg a4 a Wl = ~ PH ae tie te Wer SF 60 eT THe |p [| : Sof Segisy iy ; ies, |b a co re al ‘ ec PROFILE OF FIELOWORKS Fig. 8. The thickness of ordinary earth required to resist penetration at usual battle ranges is 3 ft. for rifle fire, 10 to 24 ft. for field guns. Plate No. 8 shows a profile-of field works on which the names of the component parts are indicated. -Plate No. 9 shows our standard profiles as outlined in our Regulations. Plate No. 10 shows a progressive trench profile adopted from German and English regulations. | tyme *For single shot. tIn sacks, about one-half these figures. 19 LSFT. COMMAND STANDING TRENCH ENLARGED TIME TO CONSTRUCT (SOFT GROUND) 2 TO +4HOURS PER YD OF LENGTH ae a ee ee L.SFT. COMMAND SPLINTER PROOF TIME TO CONSTRUCT(SOFT GROUND) 2T0 4 HOURS PER YD. | rrr AREA 14,75 SQ.FT. an eee Lae af a: 2FT. COMMAND STANDING TRENCH TIME TO CONSTRUCT (SOFT GROUND) 2TO4 WARS. PER YD. OF LENGTH +4.8.S. Fig. 9. 20 / OVERHEAD COVER. Overhead cover should be provided wherever and whenever possible. This need not necessarily be of massive nature, but in many instances it need only be sufficient to give good concealment. Our Engineer Field Manual gives us the following information regarding thickness of overhead cover: For splinterproofs 6 to 8 inches of earth is necessary with a timber structure sufficient to carry the load. For bombproofs a minimum thickness of 6 inches of timber and 3 feet of earth is necessary against field and siege guns and 12 inches of timber and 6 ft. of earth is necessary against howitzers and mortars of a heavy siege train. A German military engineer recommends a thickness of earth equal to twice the depth of penetration of the shell before bursting and a supporting structure of sufficient strength to safely carry from 2 to 4 times the weight of earth coming on same. Col. von Schwartz states that during the siege of Port Arthur PROGRESSIVE TRENCH ADAP TES FROM GERMAN & ENGLISH REGULATIONS Ce? lg ke CF) S04 Revatwenf Broan KNEELING TRENCH IST STAGE 1HR STANDING TRENCH S*° STAGE SGHRS-SVHRS KNEELING TRENCH WIDENED FOR PASSING STANDING TRENCH WITH OVERHEAD COVER ESS STAGE 2HRS 4TH STAGE GHRS-/JOHRS Fig. 10. a 5-ft. thickness of clay tamped in one-foot layers and placed over a concrete roof successfully withstood the repeated action of a 6-inch shell. For concrete covering Colonel von Schwartz recommends a thickness of 9 ft. to resist the 1l-inch shells, such as were used at Port Arthur. Our sea coast fortifications are provided with a 10-ft. Portland cement concrete overhead cover. An earth covering from 5 to 10 ft. in thickness placed over concrete roofs greatly assists in taking up the impact of the shell. _ The German practice in the present war is to provide dug-outs from 25 to 35 ft. below the surface and in front of their trenches. ‘These dug-ouis are reached by half-galleries. Plate 11 shows two types oi these dug-outs with galleries for same. The British pro- vide recesses in their front trench walls, as shown in Plate 15. 21 LOOP HOLES. The use of loop holes must be determined by the local condi- tions. The chief disadvantages of the loop holes are the reduction of rifles and the restriction of the fire to a frontal direction. Visible loop holes are very dangerous and to aid concealment the rear of the loop hole should be shut off from any light. As concealment is one of the most important factors in trench warfare, the use of loop holes is very common in the present Euro- pean War. The most serviceable form of loop hole consists of a pyramidal box made of 2-inch plank with a steel plate spiked on small end of same and pierced for fire. The steel is % inch thick and the opening in same is about 2 inches by 4 inches. This open- ing is usually provided with a movable lid which closes the opening when not in use. This is known as the “hopper loop hole.” SANO BAGS = AccES8S THRY very ~ Pe 4 SLOPING HALF GALLERY ' | 4 i’ GERMAN DuG OUT OF THE PoRsTlLne. TY tte LTT = rr | osha I < 7 Aw) Thay) ee a ee 1X) ; f of al w & oe ~ 4) oil 10g ati SECOND TYPE OF GERMAN DuG-OuTr FiG.2 ig dd. Loop holes can also be readily constructed with sod or sand bags. Loop holes must not be closer than l-yard intervals. If placed | closer they will weaken the parapet. All loop holes must be masked so as to avoid discovery by the enemy. A continuous loop hole may — be readily constructed by placing two 14-inch diameter logs along and above the parapet with supports 14 feet apart. The logs raised from 3 to 6 inches above parapet so as to give the men sufficient space to fire through. Concealment can be secured by throwing grass or dirt over logs so as to blend with the surroundings. 22 DRAINAGE. The drainage of trenches is of great importance. When trenches are constructed under threatening weather conditions, or where trenches are constructed near the foot of a hill or in low level country, drainage becomes a prime necessity even if the trenches are to be occupied for only a comparatively short time. Trenches should at all times be made as dry as possible. The floor of the trench should be made to slope backward to a small drainage ditch or gutter which carries the water to a sump-or to a point where it can be disposed of otherwise. Hand-operated pumps or small power-driven pumps can oft’times be used to good advan- tage. Provisions should always be made for excluding surface drainage when constructing trenches on the side of a hill. Fascines laid on floor of trench will aid very much in keeping the feet dry. Nothing will take the fighting spirit out of a soldier quicker than will wet feet or wet lower garments. ARTIFICIAL CONCEALMENT. With the extensive use of the high power weapons and the howitzers of small and large caliber, the question of sufficient thick- ness for both horizontal and overhead cover becomes a serious and difficult one. The author fully agrees with the school of military engineers who believe that the best protection lies in concealment and mobility. Even if the protection by thickness of cover alone would be advisable at times, the element of available time will enter into the problem and in many cases will not permit the construction of sufficient thickness of cover. Low parapets, sodded parapets, the entire omission of parapets, avoidance of skyline, certain backgrounds, narrow trenches, curved traces and concealment of disturbed ground will aid greatly in securing concealment. Obstacles must also be concealed to avoid their destruction by the enemy’s artillery and further avoid aiding the enemy in locating the position by means of the obstacles. Light- ing systems should be of a flashing rather than of a constant nature. The author again wishes to bring the reader’s attention to his canvas system of concealment, as:shown on Plate 3, for infantry trenches, and on Plate 17, for permanent fortification. Canvas will not only offer good concealment by giving it the color of the-sur- roundings, but it will also furnish protection from the rays of the sun and from rain, sleet and snow. Even the armored turrets could be concealed to good advantage by means of this material. The canvas could be made up in rolls so that it could readily be handled by two.men. CLEARING THE GROUND. Clearing the ground to obtain a good field of fire should be given very careful consideration. A clear field of fire of 100 yards in front of the trenches will be sufficient if it cannot be extended 23 without loss of concealment. Large trees in standing position give less concealment than when lying on the ground. Thickets and brush can be cut down or burned. Large high-standing crops, such as corn, cane, etc., can readily be tramped down by cavalry or leveled with horses hitched to some kind of a drag. Special atten- tion should be given to objects which will afford probable conceal- ment for the enemy’s artillery or machine guns. These objects should be destroyed. If the sacrifice of labor and time is not too great and good concealment is not sacrificed, a field of fire of 800 yards will oft’times be found of great advantage. OBSTACLES. Obstacles assist in strengthening defensive positions. Obstacles should form no shelter for the enemy. Obstacles should be sheltered from the enemy’s artlleme fire wherever possible. Obstacles should be difficult to remove. Obsta- cles should not interfere with counter attacks. Obstacles should be placed from 25 to 100 yards from the trench. Obstacles should be concealed. This can be accomplished by scattering small pieces of brush over same but this brush must not be of such density so as to afford a screen for the enemy. Another effective method is to provide a shallow wide trench for wire entanglements, etc. Col. Fiebeger, in his work on Fortification, gives us the follow- ing information relative to obstacles: “Obstacles are employed in connection with fortifications to protect the works from surprise, to break up the assailant’s forma- tions, and to hold his troops for a time under the accurate fire of the defender. They should be concealed from the assailant, they . should neither give him cover nor conceal his movements, and they should be difficult to destroy. Obstacles may be placed either in front of or along the line of defense. If in front of the line, they are most effective if they are under the close infantry fire of the- trenches, under close observation at night, near enough to the line of defense to compel the assailant to cease his artillery fire before his infantry reaches them, and far enough from that line to save them from destruction during the artillery bombardment which precedes the infantry attack. - Obstacles along the. line are either in the ditches of the fortifications or in the intervals between the works of the intrenched line. For passive defense the obstacles in front of a defensive line should be continuous; for active defense they are employed only in the defense of salients or key points.” Plate 12 shows different types of obstacles, including some of the latest types used by the German army. DUMMY TRENCHES. Dummy trenches are useful in diverting the enemy’s fire. These trenches are usually constructed with the waste ground from the 24 regular trenches or they are quickly constructed by means of horses and plow. The appearance of these dummy trenches must be of such appearance so as to deceive the enemy, otherwise it is very apparent that they will fail in their purpose. EXECUTION OF THE WORK. Fortification, like all other work, should be executed in the shortest possible time and with the least fatigue of the men. The officer must bear in mind that 2 hours of digging will leave a soldier fit for both fighting and marching, while 4 hours of con- tinuous digging will unfit him generally for either fighting or march- ing. | | 3? | In executing the work the first step is to mark on the ground the projection of the interior crest, sometimes called the firing crest. It may be marked continuously by stretching a line or by CEE SB A PS PROTECTED ENTANGLEMENT OBSTACLES Figs: 12: scratching the surface with a pick. The author suggests that a line. be stretched at a height of the interior crest supported on stakes set 11 paces or approximately 9 yards apart. These stakes will mark the length of a squad trench with an allowance of 1% feet on each side for a traverse. The second step is to determine the depth and width of trench and to check the height of parapet so as to assure a clear field of fire. The third step is to mark the toe of parapet and also lay out the ditch if one is required. This is best accom- plished with stakes set about 2 yards apart. Working parties should be made up so far as possible of entire organizations. A battalion should be ordered to send one, two or three companies; a regiment, one or two battalions, and a brigade, one or two regiments. Work should be performed by complete units—this will greatly 25 assist in control and placing responsibility. The author believes the best results can be obtained by assigning one squad to each 9 yards of trench (this is the squad length, 1 yard per man and 1% feet at each end for traverse) with a corporal in charge of each squad. The corporal is held responsible for the men and work performed. To place a detachment on the work, the organization comprising it approaches the tools in column of files, rifles slung, pass between the piles of tools, shovels on the right, picks on the left. Engineer soldiers at each pile hand tools to the men as they pass. The cor- poral or squad leader places himself alongside the rear file of his squad, he takes a shovel while the file on his side takes a pick. Each squad leader then conducts his squad in column of files to the rear of the portion of the trench to be constructed by his squad. He usually halts his squad about 3 yards in rear of the cutting line and parallel to it. Work is started at the command: Commence work! The work should be divided into 2-hour tasks for each man. Weather conditions must at all times be taken in consideration. There should be one-sixth more men than theoretically required. Assuming men at 5-foot intervals and neglecting fractions the num- ber of hours required to dig a trench, is the section of trench in square feet divided by 5 for easy; 4 for medium, and 2! for hard soil. The table below gives the amount of work that can be accom- plished in one hour by one man: EXCAVATION— In easy soil— First, hoturcta.d 6s VPS SSP Rs es ee ee cubic feet, 30 Second Hotri .) cong bike hae ee eae eta cubic feet, 25 Third ‘hour 76, 3 ses sees oe cies sd ee ee cubic feet, 15 Thereafter contmuotis work....). 220.2. eee ee cubic feet, 10 in hard soil, about half the above. In loose earth, 60 cubic feet. Filling sand bags, 20 bags (0.5 cubic foot each). REVETMENT CONSTRUCTION (Material and tools on hand)— Rough brush woodsor, plank ye. ao. eae es sq. ft. per man, hour, 40 Brushwood hurdles, rough— Making vee OR eeOnG storie eee ce ee ne meee sq. ft. per man, hour, 15 Placing 3220) Pio Mee NOs aR a eae sq. ft. per man, hour, 30 Sand bags— Pilling cat. aeeaihart wetagenios.c, eotae aie Ratt cutee sq. ft. per man, hour, 10 Placing Give ic aa eter orleans en oe sq. ft. per man, hour, 20 Sod— Obtaining SGe FOr cates oe der ules ee eee sq. ft. per man, hour, 7 . PIACing a ee ie eRe en See sq. ft. per man, hour, 10 OBSTACLE CONSTRUCTION (Material and tools on hand)— Abattis, wired x1 strong tow) oJ. fe la tate ee eee linear feet, 1.5 Wire entanglement— High | ites tad 258 sh cee fe ner ed Ga eens square feet, 27 LOW sss oho eee eke, oe Sel ti ap Shane od ete aera square feet, 90 By working in two reliefs above figures can be increased by one-third. 26 Ss CLEARING— Bmickets up tod.5)inches diameter... 2. cl.s.. seh oe. square yards, 25 Light clearing of soft woods, trees to 12 in. in diameter.square yards, 25 MMTENENL.) CLOT AST Pid. titre Sifet Mates lsd acbiaia ca ah «o's vee square yards, 15 Plate 13 shows in outline the general method of laying out and proceeding with the work. OBSERVATION, TELEPHONE, WATER SUPPLY AND MAGAZINES. ‘Well concealed and well located observation stations are very necessary for a fortified position. These stations must afford the observer a maximum amount of cover and concealment, consistent with the performance of his duties. A complete telephone system is necessary so as to afford ready communication with all parts of the fortified position. With a com- te Picks BHOVELS ULL i ENGINEER SOLDIER \ eee ae ee oe eee ey eee ee Mind ae ef Picea) Neen QUARTERS igen ts: \ | | | | | A ] plete telephone system, guns of the same batteries can be scattered over considerable area without the loss of fire control. Good drinking water must be provided for the soldiers who occupy the trenches. Clean water is also a help for the “‘first aid” of the wounded. The arrangement to be made will depend on the local requirements and conditions. Special magazines are not necessary. Recesses cut in front wall or cartridge boxes placed at convenient places will generally fulfil the requirements of ammunition storage. 27 Sk La ee Td AD oe! aE! FRY SM ARARE Met ite iy Bee TGA an REE eae nen Nae A GERMAN FORTIFIED POSITION. Major General Mayer proposes the following arrangement of a defensive position: As he considers that observation from aero- planes may obviate the difficulty of locating the exact position of the defenders’ shelter trenches, and he thinks a distinct difference should obtain in the defense against distant fire and against the close attack and assault. He constructs an advanced line of fire trenches for defense against the close attack and 100 meters behind this a second row of cover trenches, connected by approaches with the front line. Both are dug out on the front slope of a hill below the crest, the rear or cover trench being about 200 meters in front of the line of guns just behind the crest. He proposes to have no wire entanglements as obstacles because these would be easily seen and give away the position; but to have land-mines constructed 150 meters in front of the front fire-trenches. Machine gun sections should deliver frontal and oblique fire between the land-mines and the front line of fire-trenches to meet the close attack. Also machine guns for more distant frontal fire effect should be in posi- tion behind the line of cover-trenches. Machine guns in pairs should also be placed for flanking fire in or behind the shelter-trench for the close defense. This system cannot be spoken of as multiplying the defensive lines. It is a single line, if you consider that the second trench is simply a line of trenches arranged as a cover-trench for defense from distant fire. The designer pictures to himself the course of the action thus: The airmen have from their great height only been able to observe the ground very generally. The machine guns being easily masked, would remain unnoticed. The guns and rear line of machine guns open fire, say, at 1,500 meters, against the hostile infantry advancing cautiously to the attack. The line of defenders told off for distant fire would only open fire when the attackers reinforce strongly, then they use rapid fire. No shot is fired out of the front fire-trenches until the attackers come within 300 yards. Then the machine guns in the front line open fire and oblige the attackers to bring up field-guns to engage them. The men in the front shelter-trench fire open fire when the attackers are about 150 meters off and the mines have begun to act. This would be the moment for the counter-stroke by the reserve, which has been kept back concealed. The decisive line of defense is thus undiscovered until the decisive moment, which the defender utilizes to repulse the attack. BRITISH TRENCHES. The following remarks are extracted from Instructions in Field Training for the British Army. They are based upon the experience of the European War. They are especially applicable to fortifications which are to be occupied for a relatively long time and in relatively close proximity to similar works of the enemy. They are also of special interest as indications of the very great 28 power of modern weapons and the resulting necessity for conceal- ment from view: Trenches should be located so that they are not under observa- tion by hostile artillery. Possible observing stations on ground occupied by the enemy should also be considered. This conceal- ment is regarded as of greater importance than an extensive field of fire. | A field of fire of 100 yards will be sufficient if it cannot be extended without loss of concealment. Obstacles in front of the trenches must be carefully concealed, as otherwise they will assist the enemy to locate the trenches in rear. A location for the trenches back of a slight rise or back of a second hedge with obstacles hidden or entangled in the hedge in front has been found to afford satisfactory concealment. Modern artillery fire is practically continuous and the accuracy of ranging phenomenal. Accordingly, the target must be reduced to the smallest possible dimensions. This is best accomplished by making the trenches as narrow and as deep as possible with practi- cally no parapet. Support trenches especially should be made deep. The support trenches should be about 40 yards in rear of and parallel to the fire trenches with ample communications to the latter. To these most of the men retire during a bombardment, leaving as few as possible in the fire trenches. Eighteen to twenty-four inches is sufficient width for a trench. As this does not permit of the free passage of men along the trench, communication is secured by means of a narrow trench about 15 yards in rear of the firing trench and connected to the latter at each traverse by a narrow passage of the same depth. (See Plate 14.) The fire trenches should be of the recessed traversed type when- ever time permits, traverses about 5 feet wide at the base and 35 feet center to center. (See Plate 15.) Surplus earth from the trench excavation should be spread or sodded, depending on the nature of the soil. A bank of earth as a parados should be placed behind and close to the trenches for protection against the back blast of high ex- plosive shells, provided this can be done without rendering the trenches conspicuous. These parados should be sodded or other- wise concealed in the same manner as the parapet. Dummy para- pets may be constructed with surplus earth. Recesses under the parapet must be ceiled. If planking or other similar material is available time and trouble may be saved by laying the ceiling for the recesses on the ground at the front of the trench, with a good bearing at the ends, and then excavating the recess and throwing the earth on top of the ceiling to form the inner part of the parapet. The recesses serve to protect their occupants from shrapnel fire. Elbow rests should be omitted or made very narrow. Most of the men will prefer to make their own niches for the forearm. A 29 device to ensure proper aiming in the absence of lights during a night attack is desirable. Head cover and overhead cover are usually impracticable, ex- cept at points to be used as observing stations. They restrict the use of the rifle and bayonet. Where head cover can be constructed to advantage a continuous loophole is the best form. } The arrangement of trenches should be such as to develop as much frontal fire as possible. Attacks by the enemy usually occur at frequent intervals at night along the whole line. Under such conditions adjacent sections of the line can give but little support to each other by crossing fire. As cross and flanking fire is not to be relied upon, straight trenches are preferred. FuRING TRENCH = TRAVERSE GENERAL PLAN OF MODERN BRITISH TRENCHES Fig. 14. Dressing stations and latrine may be provided in recesses in the support trenches. Drainage should be considered in laying out the trenches. When practicable they should be drained to a low point in the locality. When this is not practicable, sump holes must be pro- vided in the trenches, to be pumped or baled out. Machine gun emplacement should be on the flanks of a section and as well concealed as possible. They should not be unmasked too soon, as this exposes them to premature desta by the hostile artillery. Cover required for the reserves will depend upon their distance in rear of the firing line and the enemy’s ability to search with fire 30 the ground in which the reserves are stationed. The possibility of observation by aerial reconnaisance must always be considered. Obstacles must be provided to check the enemy’s attempts to rush the trenches. Barbed wite is the most effective obstacle, especially if. well concealed. The advantage of concealment, in addi- tion to preventing the use of the obstacles as range marks for the trenches in rear, is that working parties are enabled to repair each night any damage to the obstacles. This repair work must fre- quently be carried out not over 100 yards and occasionally not over 90 yards from the enemy’s trenchés. High wire entanglements involving the use of posts extending 3 feet 6 inches or 4 feet above the ground are impracticable owing to the difficulty of concealment and of repair. The driving of such posts is out of the question when DETAIL PLAN OF RECESSED AND TRAVERSED BRITISH FIRING TRENCH ENLARGED SECTION A-A Fig. 15. hostile trenches are in close proximity. Various substitutes for these posts may be employed, such as tripods, constructed of the limbs of trees lashed together, carried out and set in front of the firing line at night, at intervals of about 15 feet. The tripods are anchored to the ground and barbed wire laced between them. Any light, strong, portable support for barbed wire entanglements is ‘acceptable. Flare lights shielded on the side of the defender may be ~ employed. | If the flank of a line is refused, the trenches should be echeloned to the rear. Otherwise the trenches on the flank will be subject to enfilade fire, especially by heavy artillery at long ranges. 31 » The following observations of the aeronauts will be of assistance to those engaged in the construction of field fortifications: 1. A long continuous line of trenches is more visible than groups of trenches. 2. Straight trenches are conspicuous. 3. Trenches across plowed fields are easily distinguished. 4. Straw spread in the bottom of trenches renders them con- spicuous. 5. Trenches against hedges cannot be distinguishable. 6. It is difficult to tell whether trenches or gun emplacements are occupied. 7. Tracks to emplacements are easily distinguished. 8. Trenches should be covered with brush to hide deep shadows at bottom. 9. The operations on the European battle fields: closely re- semble the methods which have hitherto been considered charac- teristic of sieges. Sir John French says: ‘In war as it is today, between civilized nations armed to the teeth with the present deadly rifle and machine gun, heavy casualties are absolutely unavoidable. For the slightest undue exposure the heaviest toll is exacted. The power of defense conferred by modern weapons is the main cause for the long dura- tion of the battles of the present day, and it is this fact which mainly accounts for such loss and waste of life. Both one and the other can, however, be shortened and lessened if attacks can be supported by a most efficient and powerful force of artillery available; but an almost unlimited supply of ammunition is necessary, and a most liberal discretionary power as to its use must be given to artillery commanders. I am confident that this is the only means by which great results can be obtained with a minimum of loss.” PERMANENT FORTIFICATION. The ease with which the Germans successfully captured Liege, Namur, Antwerp, and the camp retranches of Maubeuge, Lille, Laon-La Fere and Rheims, all very strong positions on paper, has proved rather damaging to the prestige of permanent fortifications. -Yet there is no case for a wholesale condemnation of forts when circumstances are carefully examined. Both Belgian and French fortresses were sadly out of date in armament as well as in defensive organization, and were crushed at long range by an artillery of superior caliber (280, 305 and 420: millimeters—11.032, 12.017 and 15.548 inches) to which they could make no effective reply. To the admirably handled German heavy ordnance that fired with in- credible accuracy at ranges of ten to fourteen kilometers, the French fortress artillery could only oppose, together with obsolete mortars and insufficient field guns, weapons of 155 millimeters (6.107 inches) with a range of little over 8,000 yards. No attempt was made to defend Lille, Laon and Rheims, totally out of date and not thought to be worth the huge garrisons which 32 they would have absorbed. Maubeuge alone offered a stout resist- ance, though perhaps not so long as could have been expected from its new (but under-gunned) forts and from its garrison of 30,000 men, including nine infantry regiments and a few artillery battalions, mostly reservists. That place-forte, besides having no long range cannon, was filled by tens of thousands of helpless Belgian refugees, mostly women and children, which constituted a source of weakness. After a ceaseless night and day bombardment, lasting from August 23 to September 7, in the course of which the garrison did its duty, attacking continuously and inflicting over 20,000 casualties on the enemy (so much was admitted by German officers), the governor, Gen. Fournier, surrendered a town on fire, full of dead and wotinded, the forts of which were reduced to heaps of ruins. Only a few thousand men of the garrison succeeded in breaking through the lines of the besiegers. It is estimated that Maubeuge rendered considerable service in delaying for two weeks the advance of an important portion of the hostile artillery and in preventing the enemy using the most direct railway line from Liege to Paris. The same is true also of the obsolete fortress of Longwy, where 3,000 Frenchmen stopped for twenty-one days part of the Kronprinz’s army, winning war honors from the victor, and of the old (1874) fort of Troyon, with a garrison of 470 men, which the enemy was confident of reducing in a few hours, but which resisted an intense bombardment of five days, repulsed three brave attacks of German infantry, and cost nearly 2,000 casualties to the besiegers. But, of course, reliable information as to the value of thifea: tions can only be derived from a study of the way modern fortresses have stood the test of war. Now, the camps retranches of Verdun, Toul, Epinal and Belfort are the only ones that deserve at all to be called modern, having been the object of ceaseless improvements in recent years, though at the beginning of the war they were not quite up to date in armament, not having received the long range naval guns that now arm them. And it is a fact that they have up to the present defied the whole might of heavy German guns ‘and the repeated and well-led attacks of the masses of German infantry, especially Verdun, which is yet partly encircled, though at very long distance—over 20,000 yards. From reliable source we further learn that the excellent resist- ance offered by the Verdun fortifications is also due to the fact that many of the large guns were removed from their permanent em- placement and were then placd in concealed positions from which they could be readily moved in case the enemy discovered the position. Several semi-permanent emplacements are provided for each eun. The small circular fort, with its batteries, powder magazines -and garrison quarters crowded over a limited area is a thing of the past. The permanent fortification with mobile and concealed bat- 33 teries distributed over a large area, and well placed and concealed infantry intrenchment is and will be of great value. This is the opinion of some of our army engineers and some of the foreign military experts. | The author herewith sets forth the requirements and conditions which he believes are necessary to withstand successfully the attack of the present high power weapons: | Superiority of range and armament. Concealment and mobility of armament. Wide area of operation. 4. A cleared area around site of fort. Seelt all BS ART RE EEN EAREA OR ~ pate ssealss et x ARE > os Y Saas AKKY “ay AC.LES A sr x», FORT 640 ACRES TRencH ~ Mm we At RAST *~ —rFrE % DR RA Pe te KR RRA RR RRAKRA oy o SUNKEN ROAD eR KAREA OM Any Re AY tea ee TR Rie tek SOG ey aa Bike mas a eg raed oe oe brie oe F OBSTACLES ene? MR ML DeTe KR 96 5 GR Ane orl AD, Ie AO Ree eas ei Fie. 16 Modeled after the sketches of the 1g. 10. fortrass of Ossewetz | taken by Major Robert R. MeCormiek 5. Well placed and concealed obstacles. 6. New type armored turrets. 7. Dummy turrets. 8. Concealed infantry trenches. 9. Centrally located magazines. 0 1 Cover for garrison. ‘Covered and concealed communications between the differ- ent parts of the fort. 12. A.complete telephone and wireless system. 13. A complete lighting system. 14. Ample water supply. Plates 16 and 17 will give a general idea of the author’s plan 34 A "LT “317 Li Sti Ia NEWAINYS BH tiadvo MatA AYNOILoDaAS " S¥MLagvo 40 |. asv> NI BOVSS ld / Pi vusve y, fj 4/ F Ly) re] 4 2 ra) 2 4 a 0 oy 2 m n 2 BP 352 2m 40 EE 22 of 2 ? ; QatwaDNoo\s 414 3yyuni +3aHnua Gysowuy NOlLAVAUASaO Lsyanra SLIsOnond AwHWwng NAO as twa DNODd LY ) LAU CaBOWAY a WN ae, : wr | WY NOMvOIi4tL you NaGQOW G3S0Od0Osd Y 40 MOIA AYUSNSS 35 of a modern permanent fortification. As to the thickness of cover, lighting system and other exact data and details we must await the further developments of this present war. SEA-COAST FORTIFICATION. General Bernard, in one of his reports, outlined the use and purpose of seacoast fortifications as follows: “Seacoast fortifications must close all important harbors against an enemy and secure them to our commercial and military marine. “Second, must deprive the enemy of all strong positions, where, protected by naval superiority, he might fix permanent quarters on our territory, maintain himself during the war and keep the whole frontier or coast in perpetual alarm. “Third, must cover the great cities from attack. yee ourth, must prevent, as far as practicable, the great avenues of interior navigation from being blockaded at their entrances into the ocean. “Fifth, must cover the coastwise and interior navigation by closing the harbors and the several inlets from the sea which inter- sect the lines of communication, and thereby further aid the navy in protecting the navigation of the country. “Sixth, they must protect the great naval establishments.” Wars of recent years, as well as the present European War, have demonstrated that it is practically impossible to reduce seacoast fortification, if properly defended, by ships’ fire, and, when fortified posts have fallen, such a result has been secured by land operation assisted by a blockade. The proper land defense in connection with coast defense is therefore an absolute necessity. An effective. system of coast defense must consist of land batteries, with their protecting guns and searchlights, submarine mines, torpedoes, torpedo and submarine boats, floating defenses, barricades, dams and proper land defenses. To prevent distant bombardment by a fleet, and also to prevent the forcing of a passage or a running past the defenses, high-power guns are required for disabling or silencing battleships and cruisers at long ranges, and in addition to the mines smaller guns of the rapid-fire type are needed for similar purposes and to repel torpedo- boat attacks at the closer ranges. Sea-coast fortifications are best protected from the attack from the land side by mobile troops well entrenched and supported by sufficient mobile artillery. The heavy guns and mortars should also be designed so that they can be turned and used in the land defense. Mines are and should be considered as obstacles and in order to accomplish their object must succeed in holding the enemy in the zone of greatest effective fire. They must allow safe passage of the vessels of the defense but must be instantly dangerous to the enemy’s ships. The United States coast defense is provided with 8-inch, 10-inch, 12-inch and 16-inch caliber guns for heavy armament. The mortars 36 are mostly of 12-inch caliber. The rapid-fire armament consists of 6-pounders and 15-pounders and 5-inch and 6-inch caliber guns. The long range guns are usually placed at a height of 165 to 250 feet above sea-level. The mortars are usually placed at a height of 260 to 300 feet above sea-level. The lighter and rapid fire guns are usually placed at height of about 60 feet above sea-level. Three systems of range finding are now in use: 1. The horizontal base system with a horizontal base along shore and which has an observation station at each end of this base. The target is located by the intersection of the lines of sight from the two stations. 2. The vertical base system with the vertical height of instru- ment above mean low water as the vertical base. The distance to 3OTosOVYos 150 TOGOOYDS G 7 A Y) j y Y Y} Fi REDAN With CURTAIN Counten- & SCARF wale SOUNTER-SCARF ERY CREMAILLERE Tae? aN 6ooTe 1200VOs4 FIELD WORKS in COMBINATION a ne BASTIONES FORT Hes Fig. 18. the target is read off the instrument in yards directly when the horizontal cross-wires of the telescope is directed on the water line of the target. The azimuth is obtained on the graduated horizontal circle. 3. The third system is the coincidence range-finding system, which requires a single station equipped with a coincidence range finder. This range finder is equipped with an azimuth reading device. For protection and cover, some of our sea-coast fortifications are provided with 15 feet of concrete and 45 feet of sand for walls exposed to horizontal fire and 10 feet of concrete where exposed to vertical fire. Mobility and concealment of armament should receive special 37 attention in modern fortification. Some of the large European, fortresses are equipped with heavy mobile armament and which 1s protected with steel cupolas. Conditions for good mine locations are shallow water and gentle current. A depth of about 100 feet and a current of about 7 feet per second are the respective limits. Excessive tide ranges (over 10 feet) require a double system of mines; one in front for low water and another in rear for high water. The mines should be laid checker-board fashion with in- tervals not greater than 60 feet. Electric contact mines are generally used in coast-defense -with their cables connected to the firing station on shore. All mine fields looo Zvoe SCALE (N METERS J | 35 (25) Pot ( w3 LPs) (NNER PUNES (5) y “ee, = SRE oes.sta.” YJ ma r S Ral ») Reo >) Wihamicare® yee Ses wren\ AE eRRE (se) should be protected by rapid fire guns usually placed on the flanks of the mine field. Two examples of effective sea-coast fortification of the present European War are the fortifications of the Dardanelles and the fortifications of the Island of Helgoland. The fortifications of the Dardanelles have successfully withstood the combined naval and land attack and have inflicted severe losses on the enemy, both in ships and men. The fortification of the Island of Helgoland may be classed as the greatest military engineering work of this age. A 38 small barren and rock-strewn island has been transformed into a formidable defensive work and so well has the work been planned that Germany’s entire navy finds absolute protection behind this island, against the attack of the greatest navy that has ever cruised the waters of the world. To illustrate a modern fortified harbor, the system of the Austrian, Colonel Mielichhofer, is reproduced in Plate 19. The surrounding country of this harbor rises to 60 meters above sea-level, which permits of easy fortification. The inner harbor. allows of the location of arsenals and magazines which are entirely covered by the heights, so that these works are not only protected from bombardment by distance, but also by their position. The inner harbor is of sufficient area to accommodate the entire ee , ——-—— BASE ENO——— TH $$ = = STATION “8 ve Ss RG e; > Ta Tron SY u.S. COAST-OEFENCE FORTIFICATION Bie 20. fleet. The harbor entrance is quite narrow and easily obstructed, thus making it very easy to defend. | There are two mine fields provided—an outer and an inner. The outer mines surround the entrance proper at a distance of about 2,000 yards and this mine zone is located in the most effective zone of fire of the heavy coast guns. The mines are located and arranged in a double row. The mines nearest to shore are judg- ment mines, which permit the vessels of the defense to pass over them uninjured, while the others are contact mines. The inner obstructions consist of a submarine dam at the center of the entrance with passages at each end which are closed by judg- ment mines. In rear of these mines barricades are placed. The mine fields and barricades are flanked by rapid fire batteries 39 and shore torpedo batteries. The field of fire is illuminated by means of searchlights. | Plate 20 shows a typical sea-coast fortification in detail. Bee é « a eS \S = Ss ae a AN fe Ys THE GERMAN MOVABLE TURRET 2-35.9 INCH SUNS TURRET TORTS \oe Ce SS ~\O, SRR 3 PTT : a, FEY SEG G CRN S Fig. 21. Plate No. 21 shows a Belgian steel turret fort; also a German portable turret. These steel turrets are usually placed in combina- tion with trenches as outlined in plan on this plate? 40 So hed Mic if as, * > |