Early in 313 Constantine and Licinius met at Milan to co-ordinate their rule. To consolidate Christian support in all provinces, Constantine and Licinius issued an “Edict of Milan,” confirming the religious toleration proclaimed by Galerius, extending it to all religions, and ordering the restoration of Christian properties seized during the recent persecutions. After this historic declaration, which in effect conceded the defeat of paganism, Constantine returned to the defense of Gaul, and Licinius moved eastward to overwhelm Maximinus (313). The death of Maximinus shortly afterward left Constantine and Licinius the unchallenged rulers of the Empire. Licinius married Constantine’s sister, and a war-weary people rejoiced at the prospect of peace.

But neither of the Augusti had quite abandoned the hope of undivided supremacy. In 314 their mounting enmity reached the point of war. Constantine invaded Pannonia, defeated Licinius, and exacted the surrender of all Roman Europe except Thrace. Licinius revenged himself upon Constantine’s Christian supporters by renewing the persecution in Asia and Egypt. He excluded Christians from his palace at Nicomedia, required every soldier to adore the pagan gods, forbade the simultaneous attendance of both sexes at Christian worship, and at last prohibited all Christian services within city walls. Disobedient Christians lost their positions, their citizenship, their property, their liberty, or their lives. Constantine watched for an opportunity not only to succor the Christians of the East, but to add the East to his realm. When barbarians invaded Thrace, and Licinius failed to move against them, Constantine led his army from Thessalonica to the rescue of Licinius’ province. After the barbarians were driven back Licinius protested Constantine’s entry into Thrace; and as neither ruler desired peace, war was renewed. The defender of Christianity, with 130,000 men, met the defender of paganism, with 160,000 men, first at Adrianople and then at Chrysopolis (Scutari), won, and became sole emperor (323). Licinius surrendered on a promise of pardon; but in the following year he was executed on the charge that he had resumed his intrigues. Constantine recalled the Christian exiles, and restored to all “confessors” their lost privileges and property. While still proclaiming liberty of worship for all, he now definitely declared himself a Christian, and invited his subjects to join him in embracing the new faith.