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Constantine was the first Roman emperor to profess Christianity. By doing so, he profoundly influenced world history. He embraced this previously persecuted religion and set it on a path that led to the formation of Christiandom.
FACTS
Constantine became emperor of the Western Roman Empire in 306 C.E and was sole emperor of both East and West from 324 to 337.
Constantine claimed that in either a dream or a vision he was assured that the God of the Christians would assist him in battle.
Attributing a certain military victory to God, Constantine "immediately ordered " that a spear in the form of a cross be placed in the hand of his own statue "in the most frequented place in Rome."
Constantine held the pagan title pontifex maximus, or chief priest, and thought himself overlord of all religions in his realm.