Constantine was the first Roman emperor to convert to Christianity, and he played an influential role in the proclamation of the Edict of Milan in 313, which declared religious tolerance for Christianity in the Roman empire. He called the First Council of Nicaea in 325, at which the Nicene Creed was adopted by Christians. In military matters, the Roman army was reorganised to consist of mobile field units and garrison soldiers capable of countering internal threats and barbarian invasions. Constantine pursued successful campaigns against the tribes on the Roman frontiers -- the Franks, the Alamanni, the Goths, and the Sarmatians -- even resettling territories abandoned by his predecessors during the Crisis of the Third Century.
he was roman emperor from 306-337 ce becoming the first emperor to convert to christianity
Constantine Constantine