The Edict of Milan was a letter signed by two Roman emperors as a proclamation of religious tolerance in the year 313 AD. These emperors, Constantine and Licinius, followed through on the decriminalization of Christianity by Galerius (in 311). Licinius and Galerius were co-emperors from 305 until Galerius died in 310. The initial decriminalization authored by Galerius served as a neutral acknowledgement of Christianity as opposed to a protected religion; indeed, nearly all religions were granted freedom with the Edict of Milan, but Christianity was explicitly named to have meeting places and property returned (that had previously been seized).
Constantine ruled as emperor over many years (from July 306 to May 337), but wars and differing alliances with contemporaries including Maxentius and Licinius required constant effort. In the years prior to his rise to emperor, he feared for his own death as a virtual hostage to Galerius. In 313, his co-emperor Licinius was to marry Constantine's half-sister Constantia to seal their commitment as co-emperors, so they met in Milan. It was during this meeting that the Edict of Milan was discussed and major points including the end of Christian persecution were accepted.
Contrary to the Edict of Milan, Licinius began confiscating the property of Christians and removing them from political office in 320 AD. By the year 324, a civil war had broken out between Constantine and Licinius, eventually resulting in the defeat of Licinius and his conditional surrender to Constantine who had promised to spare his life. Instead, in 325 AD, Licinius and his bodyguard, charged with conspiring
against Constantine, faced execution by hanging. In the days that followed, the son of Licinius (who was the half-nephew of Constantine) was also executed.
With Constantine the sole emperor of the Roman Empire, Christianity was again allowed to flourish across the entire empire, although aspects of esoteric sun-worship religions were integrated into it. Constantine is known today as the first Roman emperor to convert to Christianity. The Edict of Milan is recognized today as one of the earliest statements of religious freedom by a ruler.