who converted to christianity after winning a decisive battle
Battle of the Milvian Bridge According to chroniclers such as Eusebius of Caesarea and Lactantius, the battle marked the beginning of Constantine's conversion to Christianity. Eusebius of Caesarea recounts that Constantine and his soldiers had a vision sent by the Christian God. This was interpreted as a promise of victory if the sign of the Chi-Rho, the first two letters of Christ's name in Greek, was painted on the soldiers' shields. The Arch of Constantine, erected in celebration of the victory, certainly attributes Constantine's success to divine intervention; however, the monument does not display any overtly Christian symbolism.
East–West Schism The schism between the Western and Eastern Mediterranean Christians resulted from a variety of political, cultural and theological factors which transpired over centuries.[18] Historians regard the mutual excommunications of 1054 as the terminal event.[19] It is difficult to agree on an exact date for the event where the start of the schism was apparent.[20] It may have started as early as the[21] Quartodeciman controversy at the time of Victor of Rome (c. 180). Orthodox apologists point to this incident as an example of claims by Rome to papal primacy and its rejection by Eastern Churches.