The Battle of the Milvian Bridge takes place between the Roman Emperors Constantine I and Maxentius on 28 October 312.

It takes its name from the Milvian Bridge, an important route over the Tiber.

Constantine wins the battle and starts on the path that leads him to end the Tetrarchy and become the sole ruler of the Roman Empire.

Maxentius drowns in the Tiber during the battle.According to chroniclers such as Eusebius of Caesarea and Lactantius, the battle marks the beginning of Constantine's conversion to Christianity.

Eusebius of Caesarea recounts that Constantine and his soldiers had a vision of the Christian God promising victory if they daubed the sign of the Chi-Rho, the first two letters of Christ's name in Greek, on their shields.

The Arch of Constantine, erected in celebration of the victory, certainly attributes Constantine's success to divine intervention; however, the monument does not display any overtly Christian symbolism.