There were two Emperors in the Roman Empire called Augustus. Augustus Diocletain who ruled the Eastern Part of the empire and Augustus Maximian who ruled the western portion. Each had an assistant called a Caesar. Caesar Galerius helped Diocletain and Caesar Constantius Chlorus helped Maximain. Galerius and Diocletain both stepped down in 305 allowing Constantius and Galerius to step up as the Augustus and appoint their own Caesars.
This was the beginning of a power struggle lasting over the next seven years. The wars left the Roman Empire in turmoil as battling armies marched from Istanbul to Ireland. The final battle took place between Maxentius who controlled from Rome eastward and Constantine who controlled the western empire.
The two armies met at the Milvian Bridge on the outskirts of Rome along the Tiber River. It was expected that Maxentius would stay secure in Rome creating a siege situation. Instead Maxentius led his troops across the Tiber and formed his front line along the edge of the river. Constantine’s forces set up opposite Maxentius.
The only retreat across the Tiber was the Milvian Bridge. The bridge was narrow and had been damaged by Maxentius to slow Constantine’s crossing. To support a troop withdrawal Maxentius had a wooden pontoon bridge constructed across the Tiber.
On October 28 when the two armies fought Constantine’s army had a decisive victory. Maxentius’ army was to close to the Tiber and did not have the room to regroup and instead was forced into an unruly retreat. Unable to use the Milvian Bridge because it was so narrow the army swarmed across the pontoon bridge, which collapsed under the pressure of the retreating troops.
Maxentius drowned in the retreat. His body was recovered and the next day his head was displayed on a pole as Constantine entered the city of Rome.
The battle was the decisive event to determine who would rule the Roman Empire. As the winner Constantine was able to make the rules and among the rules was the Edict of Milan in 313. The edict removed the fledging Christian Faith from being persecuted to being accepted as a religion in the Roman Empire.
As mentioned in a picture caption Constantine had a vision the night before the battle and was directed by a heavenly spirit to have the ChiRho emblem put on the shields of his army. By doing so Constantine allowed God to guide his army to victory. Constantine is believed to have proclaimed his conversion to Christianity following the Edict of Milan. His mother, Helena, is thought to have been a Christian, which probably had a direct influence on him and his religious decission. During a pilgrimage to the holy land Helena founded churches on the sites of Christ’s birth in Bethlehem and Christ’s accession in Jerusalem.