Excerpts from Books and Wikipedia
Constantine ruled over Gaul and Spain; Maxentius ruled over Italy and Africa; Prior to the battle, Constantine had a vision of a cross with the words "By this conquer." Later as a result of a dream, he ordered the cross to be painted on the shields of his soldiers. After the victory, Constantine formed an alliance with Licinius, the Augustus in the east. They divided the empire until 324 when Constantine became sole emperor. In 313, Constantine and Licinius declared the end of religious persecution in the Edict of Milan. Constantine received Christian baptism when he died in 337. Christianity did not become the official religion until 391 under Theodosius I, who closed all pagan temples. [Furtado: 1001 Days]