Constantine’s Victory at the Milvian Bridge

In 312 Constantine brought an army across the Alps into Italy against Maxentius, who held Rome. He defeated Maxentius’s generals at Verona and advanced on the city (Zosimus, New History 2.15–16) (Origo Constantini 4.12).

Lactantius wrote his account within a few years of the battle. In it Maxentius, warned by soothsayers that he would die if he left Rome, stays inside the walls while Constantine camps opposite the Milvian Bridge. On the anniversary of his accession Maxentius is jeered by the crowd at the circus, reads in the Sibylline books that the enemy of the Romans will perish that day, and marches out. His army is beaten with the broken bridge at its back, and he is driven into the Tiber in the crush (Lactantius, Deaths of the Persecutors 44). The Origo Constantini adds that his body was recovered next day and the head carried into Rome (Origo Constantini 4.12). The pagan historian Zosimus says that the bridge had been built to collapse as a trap and gave way under the fugitives; he mentions omens but no Christian sign (Zosimus, New History 2.15–16).

The Christian sources explain the victory in different ways. Lactantius says that Constantine was directed in a dream to mark “the heavenly sign” on his soldiers’ shields, and that he did so, using the letter X with an upright line through it bent round at the top, “the cipher of Christ” (Lactantius, Deaths of the Persecutors 44). He says nothing of a sign in the sky. Eusebius, in his Church History, says only that Constantine prayed to God and to Christ for aid, and that after the victory he set up a statue of himself at Rome holding the sign of the cross (Eusebius, Church History 9.9.2–12). In the Life of Constantine, written after the emperor’s death in 337, Eusebius reports what he says Constantine told him on oath: that about midday, on the march, at a place not named, he and his army saw a cross of light above the sun with the words “Conquer by this”; that Christ appeared to him in sleep the following night with the same sign and told him to copy it; and that he then had the jewelled standard made which bore the monogram of Christ (Eusebius, Life of Constantine 1.28–29) (Eusebius, Life of Constantine 1.30–32).

The senate’s monument is more reserved. The arch dedicated to Constantine in 315 says that he overcame the tyrant instinctu divinitatis, by the prompting of the divinity, and names no god (Arch of Constantine dedicatory inscription).

The Roman calendar marks the emperor’s entry into the city on the next day (Chronograph of 354 part 6 (calendar), 28–29 October). Eusebius says that the victor set up at Rome a statue of himself with an inscription crediting the city’s deliverance to “this salutary sign”, and that he and Licinius then drew up a decree in favour of the Christians (Eusebius, Church History 9.9.2–12). The letter that Licinius published in June 313 says that the two emperors had met at Milan and agreed that Christians and all others should be free to follow the religion they chose (Lactantius, Deaths of the Persecutors 48).