After a winning a battle against Licinius in 317 A.D. Constantine won concessions including most of the Balkans and the guarantee that his sons would be in line for the throne. Then, in a final showdown 324 A.D, Constantine defeated his rival at Hadrianopolis.
The emperor now turned his attention to the construction of a new capital at Byzantium (Constantinople) which took six years. Then, in the 330s A.D, he was engaged with the Germans along the Danube, defeating the Goths in 332 A.D. and the Sarmatians in 334. These victories brought back to Rome much of the Dacian territory originally won by Trajan.
Constantine died in 337 A.D. after being baptized as a Christian. His reign had marked two enormous changes in the empire: the embracing of Christianity and the move of the capital to Constantinople.