Who they were
Constantine the Great was a Roman emperor who reigned from 306 to 337. He transformed the empire’s religion and geography.
What they did
He won power through civil wars, including his victory at the Milvian Bridge in 312, and with the Edict of Milan in 313 granted toleration to Christianity, which he favored and promoted, calling the Council of Nicaea in 325. In 330 he founded a new capital, Constantinople, on the site of Byzantium.
Legacy
He set Christianity on the path to becoming the empire’s dominant religion and shifted its center eastward. His new capital would anchor the Byzantine Empire for over a thousand years.