→Events of the battle
Constantine, after arriving, realized he had made a miscalculation and that Maxentius had many more soldiers available than he did.
[[image:Labarum.jpg|thumb|right|The Labarum, Constantine's new standard bearing the Chi Rho, the first two letters in the name Χριστός, "Christ"]] It is commonly stated that on the evening of October 27, with the armies preparing for battle, Constantine had a vision as he looked toward the setting sun (although Eusebius of Caesarea records the event as occurring when Maxentius' army was still in Northern Italy). The tradition is that a cross appeared emblazoned on the face of the sun, and intertwined with the Greek letters XP ("Chi-Rho", the first two letters of Χριστός or "Christ"). [[Eusebius of Caesarae]]'s Historia Ecclesiastica claims that Constantine also saw the Greek phrase "Εν Τουτω Νικα", often rendered in Latin as "In Hoc Signo Vinces" - In this sign you shall conquer. Constantine, a pagan at the time whose chief god was Sol invictus, is said to have ordered his soldiers to put the symbol on their shields. Constantine later made a standard, known as the labarum, bearing this symbol, which he used in his later battles.
The next day, the two armies clashed, and Constantine emerged the victor. Already known as a skillful general, Constantine began to push Maxentius' army back toward the Tiber. Maxentius decided to retreat and make another stand at Rome itself. But there was only one escape route—the bridge—and Constantine's men inflicted heavy losses on the retreating army. Finally, a bridge of boats set up alongside the Milvian Bridge, over which many of the troops were escaping, collapsed, and those men stranded on the north bank of the Tiber were either taken prisoner or killed. Maxentius was among the dead, having drowned in the river while trying to swim across it in a desperate bid to escape.