Flavius Valerius Aurelius Constantinus (c. 27 February 272 – 22 May 337), commonly known as Constantine I, Constantine the Great, or Saint Constantine, was Roman Emperor from 306 to 337. Well known for being the first Roman emperor to convert to Christianity, Constantine reversed the persecutions of his predecessor, Diocletian, and issued the Edict of Milan in 313, which proclaimed religious liberty throughout the empire.