Constantine I (kon'stan-tin). Called The Great. Born in 272 at Moesia, the son of Constantius Chlorus by Helena. On the death of his father at York, where he had accompanied him, Constantine was proclaimed emperor by the troops. After defeating his father-in-law, Maximian, and his brother-in-law, Maxentius, who challenged his title, he was acknowledged emperor by the senate in 312. He transferred the seat of his empire to Byzantium, which was thereafter called Constantinople; i.e., Constantine's city. Constantine was baptized in 337 and died in the same year.