How did Constantine I’s campaign through northern Italy lead to the Battle of Milvian Bridge?

Following the collapse of the Roman Empire’s Second Tetrarchy, Constantine I and Maxentius emerged as rivals for the imperial throne. After years of complex civil conflict and the breakdown of previous alliances, Constantine invaded the Italian Peninsula in 312 CE, prompted in part by the goading of Maxentius.12

Constantine’s subsequent lightning campaign through northern Italy culminated in the Battle of the Milvian Bridge on the outskirts of Rome. During this march, Constantine reportedly experienced a significant religious vision—described by some sources as a dream or a sign in the sky—which led him to fight under the protection of the Christian God. The campaign ended decisively when Maxentius was killed in battle at the bridge, a victory that solidified Constantine’s role as the ruler of the Western Empire and influenced his later policies regarding the status of Christianity within the empire.12