The victory of Emperor Constantine during a civil war allowed for some of the most dramatic events in Roman history. The emperor’s tale of divine intervention at the Battle of the Milvian Bridge proved to be the key event in the legalization of Christianity and its subsequent adoption by the empire.
A Time of Trouble
The days of the Pax Romana were well over during the decades of instability and conflict that marked the Crisis of the Third Century. This dramatic series of events included several assassinations, coups, civil wars, and economic disasters.
The era of instability that started in 235 CE came very close to ending the Roman Empire two centuries before its actual collapse in 476 CE. The approximately 50-year crisis saw more than two dozen men claim the Roman throne.
Rome had broken into three separate parts by the apex of the crisis. The Emperor Aurelian (r. 270-275 CE) reunited the fragmented portions of the empire but was then murdered by his bodyguard.
The empire continued to struggle despite the reunification by Aurelian. However, Emperor Diocletian (r. 284-305 CE) effectively ended the crisis and implemented a series of reforms, including the concept of dividing the empire into four leaders, known as the Tetrarchy.
Persecution
Diocletian made several reforms that would change the face of the empire. He was referred to as a god, rather than simply the Princeps, or “First Citizen.” He also issued a number of reforms that helped presage the coming of the Middle Ages.
Diocletian made two major changes that are integral to the story of the Battle of the Milvian Bridge (312 CE). First, the creation of the Tetrarchy, which was largely centered around his experience and personal authority. When Diocletian reportedly resigned to tend his farm as an older man, the system of sharing power between four men soon collapsed into civil war.
Diocletian was also a strong persecutor of the Christian faith. While most emperors had discouraged or attacked the religion, Diocletian led the most serious era of persecution of the young faith. His methods were particularly brutal, including the removal of the tongue and execution of a Christian deacon. The emperor was swayed by the future Emperor Galerius to push an effort to destroy the religion. Christian writings and churches were ordered to be destroyed. Christians were barred from worshiping together.
Despite the fervent persecution, the faith continued to grow and represented a significant risk to the country’s traditional polytheist faith and the political order.
A New Civil War
Diocletian resigned to farm cabbages following a period of serious illness. The system that he built to end the Crisis of the Third Century soon led to a protracted series of civil wars. The conflicts would last for a generation and include the significant and decisive Battle of the Milvian Bridge.
The relative peace following Diocletian’s abdication lasted just a year. A coup brought the future Emperor Constantine (r. 305-331 CE) into prominence as the leader of one of four states. Around the same time, Emperor Maximian (r. 310-313) claimed the throne for himself and helped to spark a new civil war.
Maximian waged a war against Constantine but failed in his mission. Constantine captured the emperor and forced him to commit suicide. However, the resolution of one conflict still left Maximian’s son Maxentius at large.
The death of Diocletian’s successor Galerius in 311 CE helped to destabilize the remainder of the empire. Interestingly, the dying emperor issued edicts allowing for the toleration of other faiths and stopping the persecution of Christians.
Maxentius never held total authority in the empire and faced instability and riots. The instability set up a large conflict between Maxentius and Constantine and Constantine won a series of victories in a quick campaign through Italy.
Maxentius initially attempted to stay put in Rome, preparing for a siege but he was convinced to fight a traditional battle against Constantine. According to Roman historians, he consulted Rome’s ancient Sibylline Books, which told him that the “enemy of the Romans” would die in the battle.
The Battle of Milvian Bridge
The Battle of the Milvian Bridge (312 CE) proved to be one of the most important battles of antiquity. Its measure was doubled due to the dramatic changes to Roman religion and society due to Constantine’s actions.
Maxentius appeared to have a large advantage over Constantine as he set up his army outside of Rome. His forces doubled the size of Constantine’s but were positioned poorly, with their backs to the Tiber River.
Then the unthinkable in the Roman world happened. Constantine’s forces painted their shields with an early symbol of Christianity, the Chi-Rho. The symbol represented the first two Greek letters of the word “Christ.” There are several versions of how Constantine came to a decision, but one commonly agreed version is that he saw the sun with a cross of light above it. Depending on the version, the cross was joined with the phrase “in hoc signo vinces,” or “By this sign, conquer.”
It is not clear what Constantine really saw, or whether or not it was a spiritual or physical phenomenon. Regardless, the battle resulted in a dramatic victory for Constantine. Maxentius’s forces were routed and he drowned in the Tiber.
Constantine was now the prime holder of power in Rome and publicly thanked Christianity for the victory.
Toward Accepting Christianity
Constantine’s victory at the Milvian Bridge meant that he was now the top figure in the Tetrarchy. He would later abolish Diocletian’s system altogether and rule as sole emperor.
The new emperor was one of the last of the Roman rulers commonly called “the Great.” He carried significant military and administrative talent and made a move that no other Roman Emperor would have considered. He eventually promoted Christianity after formally legalizing the faith.
In the year following the Battle of the Milvian Bridge, the emperor issued the Edict of Milan, which legalized Christianity and provided tolerance for all faiths in the Roman Empire. Constantine’s actions allowed for the churches and property seized during Diocletian’s reign to be returned and he soon became a favorite for the growing church.
Constantine finally secured sole power after defeating his co-emperor Licinius (308-324 CE). Despite being outnumbered by Licinius’s forces, Constantine and his heavily Christian forces defeated Licinius at the Battle of Adrianople in 324 CE. Constantine chased Licinius into Asia Minor and forced his surrender and later had him executed.
Constantine soon became a leading advocate for Christians and organized the transformational Council of Nicaea in 325 CE. The Christian church began consolidating into a formal organization following the legalization of the faith.
Rome was changing rapidly.
The New World After Milvian Bridge
Constantine’s changes allowed for many of the common cultural rituals many hold to this day. This includes the creation of Sunday as a day of rest and the Nicene Creed, which declared God to be composed of three forms.
The emperor also made a series of changes that would add about 150 years of life to the suffering empire. He was able to stabilize the Roman currency, with coins often depicting Christian symbols.
Christianity would soon become the majority religion of the empire. Emperor Theodosius I (379-395 CE) issued the Edict of Thessalonica in 380 CE making Christianity based on the Nicene Creed the official religion of the Roman Empire. This Roman state church continues to this day as the Roman Catholic Church. This elevated the Bishop of Rome, today’s Pope, as the effective leader of the entire faith.
One of Constantine’s greatest contributions to the empire was the construction of the new city of Constantinople on the water border between Europe and Asia. His decision made the Greek fishing village of Byzantion a second Rome. The emperor set up the city to be a new capital, which would eventually speed up the split of the Roman Empire into its Eastern and Western halves. Situated along a series of crucial trade routes and with formidable natural geography as a defense, the city soon became the largest and most prominent in the Late Antique Period. It would later become the wealthiest city on the planet.
The Western Roman Empire would fall after a period of serious decline in 476 CE. However, the Eastern half of the empire, which was predominantly Greek-speaking and centered in Constantinople, continued for nearly another 1,000 years. The Byzantine Empire represented the extension of the ancient Greco-Roman world into early modernity. Byzantine emperors traced their lineage back to Constantine the Great, who changed the world one October day.
