id author title date pages extension mime words sentences flesch summary cache txt en-wikipedia-org-3385 Constantine Doukas (co-emperor) - Wikipedia .html text/html 1654 301 65 He was junior emperor until 1078, when Michael VII was replaced by Nikephoros III Botaneiates. Because Constantine was not made junior emperor under Nikephoros III, his betrothal to Olympias, the daughter of Robert Guiscard, was broken, which Robert Guiscard used as a pretext to invade the Byzantine Empire. John Doukas forced Nikephoros to abdicate to Alexios I Komnenos in 1081, and shortly after Alexios elevated Constantine to junior emperor under himself. Constantine remained junior emperor until 1087, when Alexios had a son, John II Komnenos. This arrangement was cancelled after Michael abdicated in 1078, whereupon Maria and Constantine retired to the Monastery of Petrion.[3][4] Maria married Nikephoros III Botaneiates, who seized power after Michael's abdication, at the urging of Michael's uncle John Doukas, but was unable to convince him to elevate Constantine to junior emperor, thereby breaking the betrothal.[5][6][7] Robert Guiscard therefore launched an invasion of the Byzantine Empire, using the broken betrothal as a pretext.[8] ./cache/en-wikipedia-org-3385.html ./txt/en-wikipedia-org-3385.txt