Battle of Milvian Bridge

Battle of Milvian Bridge (29 Oct 312 CE) was part of a civil war between Maxentius and Constantine I.
It marked the end of the Tetrarchy and the reunification of the Eastern and Western Roman Empire.

Constantine and the Chi Rho Symbol

In October, Constantine I marched down the Via Flaminia which leads into Rome and camped to the north of the Milvian Bridge.
The Milvian Bridge is situated over the River Tiber in Rome and is still standing today.
Constantine I had a dream the night before the Battle, in which he was told to put the sign of the Cross on his shields. In the sky, he also saw the first two initials of Christ’s name, the Greek letters 'Chi 'Rho'.
In hoc signo vinces ‘In this sign you will conquer’ were his famous words to his Legions, when he ordered them to paint the cross on their shields. Later, the letters became IHS from the first three letters of ‘In Hoc Signo Vinces’. It also stands for the first three letters of the word ‘Jesus’ in Greek capital letters.,
This later became the Labarum, a military standard bearing the symbol of Chi Rho, which Constantine I‘ soldiers always displayed going into battle.

Maxentius and the Sibylline Books

In contrast, Maxentius consulted the Sibylline Books before the Battle.
As a result, he decided to confront Constantine I on the 28th October because it was an auspicious day. Unfortunately, he was misinformed and would have done better to stay inside the Aurelian Walls and wait for the siege to collapse.

Instead of withstanding a prolonged siege behind the Aurelian Walls, Maxentius decided to confront Constantine I with a pitched battle. After consulting the Sibylline Books, he chose the date of his attack as the date of his proclamation as Emperor, 28 October 306 CE.
On the 28 October, Maxentius‘ army sallied out across a temporary bridge laid beside the fortified Milvian Bridge.
Constantine I‘ cavalry again defeated Maxentius‘ cavalry, and the defenders were forced back towards the Tiber. A rout ensued in which many soldiers fell or were pushed into the Tiber, including Maxentius.
Maxentius‘ body was later recovered from the Tiber, his head decapitated and put on display in a parade around Rome. After this it was sent to Carthage in Africa Proconsularis, who offered no further resistance.

Having defeated Maxentius, Constantine I allied with Licinius to defeat Maximinus Daia.
In March 313 CE Licinius married Constantine I’ sister and at the same time they jointly issued the Edict of Milan. This Edict placed Christianity on a legal basis within the Roman Empire, ending the Diocletianic Persecution.

The Eastern and Western Roman Empire are Reunited

The Tetrarchy ended and the Eastern and Western Roman Empire were reunited.
In 315 CE Constantine I built the Triumphal Arch of Constantine to celebrate the Battle of Milvian Bridge.

Milvian Bridge, Rome