Constantine Transforms the Roman Empire Toward Christianity

The Pivotal Battle of the Milvian Bridge

Michael Streich

The Battle of the Milvian Bridge, just outside the walls of Rome, in AD 312, resulted in significant changes that ultimately would enable the rise of Christian institutions in the western empire to achieve a degree of power necessary in replacing secular control once the west was overrun by barbarian hordes. Emperor Constantine’s  acceptance of the Christian God inaugurated a new official respect for Christianity well beyond simple toleration. It began with a sign and ended with military victory, replacing paganism with a new faith now embraced by the emperor.

 

“With This Sign You Will Conquer”

 

The story of the miraculous sign from heaven is recounted, with distinct variations, by the writers Lactantius and Eusebius. Eusebius’ rendering is considered the more accurate because Constantine had personally told him the story and confirmed its truth by an oath.

 

According to Eusebius, the omen was seen by Constantine and his entire army days before the actual battle outside of the walls of Rome. Constantine recounted that the sign was an answer to a prayer he had made to the God of his father, Constantius, a Christian. The sign itself displayed a cross in the font of a sun. Eusebius continues that the sign was confirmed to Constantine that night in a dream during which Christ appeared to him.

 

Lactantius states that the sign occurred the night before the actual battle and refers to it as, “a heavenly sign from God.” The triumphal arch, dedicated to Constantine in AD 315, gives an account of the battle, stating that, “with the guidance of divinity…he freed…the Republic from a tyrant.” Although the phrase does not specifically identify the Christian God, scholars point out that Constantine’s public attribution confirms the reference.

 

Saxa Rubra and the Milvian Bridge

 

Constantine’s adversary, Maxentius, a co-emperor approving Christian persecutions, left the security of Rome’s walls to confront the army approaching on the Via Flamina. Why Maxentius didn't remain behind the walls is a mystery. He outnumbered Constantine and had enough supplies to last any long siege attempted by his opponent.

 

The armies first met nine miles from Rome at Saxa Rubra, Constantine’s army routing Maxentius’ feared cavalry, the cataphracti. This caused panic among the mercenary troops that began a disorganized retreat to the Tiber, crossing the river over a crude wooden bridge as well as the more stable Milvian Bridge. 

The battleground favored the attacker as there was little room to maneuver soldiers. The unfortunate Maxentius, however, could only depend upon the Praetorian Guard, fierce fighters that fought to the death. After the battle and once inside Rome, Constantine would disband the Guard forever. Constantine led the central attack himself, pushing toward the bridge as any hope for a retreating Maxentius evaporated. Maxentius died crossing the river, pulled down by his armor, according to later accounts. Constantine entered the city on October 29, AD 312.

 

Impact of the Battle

 

The long term consequence of Constantine’s conversion and victory went far beyond the basilicas he endowed (among them St. John Lateran in Rome). Brian Tierney and Sidney Painter, in Western Europe in the Middle Ages 300-1475, assert that, “the subsequent rise of Christianity and its acceptance as the official religion of the empire transformed the whole nature of late classical culture.” 

The sign that led to Constantine’s victory may have begun that process. Before his death, the Emperor helped to preside over the Council of Nicaea, one of the most significant early church councils that detailed key elements of Christian doctrine, including the creed. 

As the centuries progressed and Rome “fell,” at least in the west, it was the Church that provided stability and leadership, its bishops functioning as both secular and religious administrators, this the long term effect of AD 312.

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