Mediolanum Agreement and Nicomedia Promulgation (“Edict of Milan”)
In 313, Constantine and Licinius agreed at Mediolanum to universal religious freedom and restitution of Christian property; on June 13, Licinius posted the policy at Nicomedia. The text promised worship “to Christians and all others.” Doors long barred swung open; archives searched for deeds.
What Happened
Two years after Galerius blinked, his successors codified a broader peace. In February 313 at Mediolanum, Constantine and Licinius agreed to guarantee free worship and to restore confiscated Christian properties without payment. The policy traveled east in Latin and Greek; at Nicomedia on June 13, Licinius issued a circular that posted the terms for all to read [6][5].
The words matter. “We grant to the Christians and to all others full authority to observe that religion which each preferred,” the circular says, and it orders that places taken “are to be returned to the Christians without payment or any claim of recompense” [6]. Eusebius introduces his Greek with, “A copy of the imperial decree, translated from the Roman language,” highlighting the bilingual reach of the act [5].
Implementation was gritty. City by city, magistrates unlocked basilicas; notaries traced titles; officials adjudicated claims. In Nicomedia, Antioch, and Thessalonica, congregations stepped into light from courtyards where purple‑cloaked officers had once posted prohibitions. The sound was the groan of old door hinges and the murmur of legal formulas.
Politically, the agreement knit Constantine and Licinius in common policy even as they eyed each other’s armies. Religiously, it ended the legal war. Christians could assemble, own, and rebuild; others were explicitly included. After a decade of coercion and two years of uncertainty, the law’s words settled a continent’s ritual life [6][5].
Why This Matters
The 313 settlement established universal religious liberty in imperial law and mandated restitution of church property. It normalized Christian institutions within civic life and created a legal template that recast the state as guarantor of plural worship rather than enforcer of sacrifice [6][5].
Within the ideology, law, and religion theme, this is the counter‑stroke to 303: statute now protected the communities it had punished. It also showcased the Tetrarchy’s administrative reach in reverse—dispatches and courts reopened what earlier edicts had closed [6][5].
In the broader arc, the agreement coincides with the Tetrarchy’s political demise but preserves its administrative strengths. Constantine would inherit a sacral, centralized monarchy that he would align with his own faith, but the legal end of persecution in 311–313 made that alignment possible without constant war on conscience [6].
Event in Context
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People Involved
Key figures who played a role in Mediolanum Agreement and Nicomedia Promulgation (“Edict of Milan”)
Licinius
Licinius, a Balkan soldier and friend of Galerius, was elevated as Augustus at the 308 settlement to stabilize the Tetrarchy’s West. He soon allied with Constantine, married his half-sister Constantia, and co-authored the 313 agreement popularly called the Edict of Milan, guaranteeing free worship and restitution of Christian property throughout the empire. Though later a rival of Constantine, in this timeline he is the indispensable partner who turned a weary toleration into a formal policy and broke Maximinus Daia’s resistance in the East.
Maximinus Daia
Maximinus Daia, a nephew of Galerius from the Balkan countryside, was raised to Caesar in 305 and ruled Syria and Egypt with a heavy hand. A staunch pagan, he intensified the Great Persecution in his territories, encouraged anti-Christian petitions, and resisted concessions even after Galerius’s 311 edict of toleration. When Constantine and Licinius agreed on the 313 religious settlement, Maximinus defied it, only to be defeated by Licinius and die in flight later that year. In this timeline he is the last holdout of the old order—ambitious, coercive, and ultimately swept aside.
Constantine I
Constantine, son of Constantius, was acclaimed by the army at York in 306 and soon transformed the Tetrarchy’s civil wars into a new imperial order. He defeated rival claimants, confronted Maxentius and Maximinus Daia, and—together with Licinius—issued the 313 settlement known as the Edict of Milan, guaranteeing free worship and the restitution of Christian property. In this timeline he stands at the hinge: the Tetrarchy’s promise of order collapses into rivalry, and Constantine reframes legitimacy around personal victory and religious toleration, opening the path to a Christian empire.
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