CONSTANTINE I proclaimed Roman emperor by his troops on this date. Constantine is perhaps best known for being the first Christian Roman Emperor. His reign was a turning point for the Christian Church. In 313 Constantine announced toleration of Christianity in the Edict of Milan, which removed penalties for professing Christianity (under which many had been martyred in previous persecutions of Christians) and returned confiscated Church property.
Though a similar edict had been issued in 311 by Galerius, then senior emperor of the Tetrarchy, Constantine’s lengthy rule, conversion, and patronage of the Church redefined the status of Christianity in the empire and marked the beginning of the blurring of the lines between Church and state for millennium. In hoc signo vinces (In this sign we conquer) he said…and he wasn’t kidding. His heirs, his three sons, proceeded to eradicate the pagans and their culture.