The Battle of Milvian Bridge

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Podcast Transcript

In the year 312, two claimants to the Roman imperial throne met outside the walls of Rome near a bridge that crossed the Tiber River. 

The subsequent battle that followed was not that different from many other Roman battles which had been fought over the centuries. 

However, the implications of that battle have long-reaching ramifications that have shaped the world for the past 1700 years. 

Learn more about the Battle of Milvian Bridge and how it changed the world on this episode of Everything Everywhere Daily.


When looking back at world history, there are great battles, and there are important battles. 

Not all great battles are important, and not all important battles are great. 

The Battle of Cannae, on which I did a previous episode, was a great battle. Hannibal and the Carthaginians defeated the Romans in one of the most lopsided victories in history. However, it wasn’t an important victory insofar as the Carthaginians lost the war. 

The Battle of Stalingrad between Germany and the Soviet Union and the Battle of Gaugamela between Alexander and the Persians were both great and important battles. 

I would place the Battle of Milvian Bridge into the category of battles that were not great but was extremely important. 

To understand the Battle of Milvian Bridge, you have to understand what was happening in the Roman Empire in the early 4th century. 

During the third century, the Roman Empire was a mess. The assassination of Emperor Severus Alexander in 235 ushered in a fifty-year period of anarchy. There were civil wars, rebellions, uprisings, and barbarian invasions, and fewer than 26 men claimed the imperial throne during this period. 

It finally ended with the rise of Emperor Diocletian. Diocletian reigned for 21 years, which was an eternity for a Roman emperor at this time, and did something few emperors ever did: he retired from power and died a natural death. 

Diocletian realized that the empire had simply become too large for one person to rule. 

To solve this problem, he created a system known as the tetrarchy.  The tetrarchy divided the empires into two halves, east, and west. 

A senior emperor would lead each side of the empire with the title of Augustus. Each Augustus would be paired with a junior partner with the title of Caesar.  The “Caesar” would be the designated successor to the “Augustus,” thus ensuring that there would be a smooth transition of power. 

The tetrarchy worked well…. for a while. 

Diocletian was the unified Augustus of the empire, and he appointed as his Caesar, a man by the name of Maximian.  He was eventually named co-Augustus with Diocletian.

In 305, in a bloodless transfer of power, Diocletian and Maximian retired, and the new Augusti was Galerius in the east and Constantius in the west. Their respective Caesar’s were Maximinus Daia in the east and Flavius Valerius Severus in the west. 

Constantius died the next year in 306 in Britain while campaigning in what is today the City of York. 

After he died, his army proclaimed his son, Constantine, as the new Augustus in the west.

Constantine, not wanting to cause a civil war, agreed to be the junior Caesar to Severus, who was now the new Augustus. 

This angered Maximian’s son Maxentius, who felt that he should have been named caesar. 

What happened over the next few years was extremely complicated. Maxentius got the Senate and the Praetorian Guard to declare him emperor with this father, then his father turned on him and then joined up with him again.  Severus marched to Rome to take out Maxentius and was killed, making Constantine the new Augustus. 

Maximian eventually tried to kill Constantine. He was caught and then was forced to kill himself. 

Galerius died in 311, which sent the entire empire into chaos. 

By 312, when the dust settled, Constantine and Maxentius were the two major claimants for the throne, and they were on a path to war. 

Maxentius controlled the Italian Penisula, Sicily, Corsica, and North Africa. Constantine controlled Britain, Spain, and Gaul.

In the spring, Constantine and his army of 40,000 marched over the Alps and headed to Italy. They took what are the modern-day cities of Turin and Milan, besieged Verona, and then headed to Rome, where Maxentius was waiting.

Maxentius’ plan was originally to wait him out behind the walls of Rome. However, he consulted with the Sibylline Books, which said on the next day an enemy of Rome would die. 

He figured that meant he was going to win, so he decided to take the fight to Constantine.

The location of the Battle was across the Milvian Bridge, which was a stone bridge that crossed the Tiber and led to the Via Flaminia.  Maxentius had also built a pontoon bridge across the river next to the stone bridge. 

The battle commenced on October 28, 312. Maxentius’ men were pushed back, and due to poor planning on Maxentius’s part, they had nowhere to go because the river was behind them. 

This led to a stampede across both bridges, with the pontoon bridge collapsing, drowning almost everyone on it, including Maxentius.

Constantine won, became the unified emperor of Rome, established a new capital city that bore his name, and became known as Constantine the Great. 

What I just described is just the Xs and Os of the story of the battle. For those of you familiar with the Battle of the Milvian Bridge, you will have noticed that I left out what is by far the most important part of the story and the thing which made the battle so important to world history. 

The details of what made the battle so important have differed over time. 

I’ll give the most common version of the story, which might just be apocryphal, but it might as well have been true for the purposes of creating a legend. 

Supposedly the night before the battle, Constantine had a dream. In that dream, he saw a cross with words inscribed on it in Greek that read, “En tout? nika.” 

In Latin, it reads, “in hoc signo vinces” and in English translates to “in this sign, you shall conquer.” 

When Constantine woke up, he asked some of his men who were familiar with Christianity what this meant. They said it was a message from God. 

Constantine then ordered all his men to paint the chi-rho symbol on their shields before the battle.

The chi-rho is the superimposition of the Greek letters chi and rho, which are the first two letters of the Greek word Kristos. It looks like an elongated letter P with an X at the bottom, and early Christian communities used it as a symbol for Christ. 

Having received a message from God and painted their shield, Constantine went on to win and converted to Christianity. 

….or at least that is how the story goes. 

Here I should note that Christians were just a minor sect in the Roman empire at the time of the Battle of the Milvian Bridge. They had no real political, economic, or military power. They had been persecuted for almost 300 years by the Romans, with the greatest persecution occurring under Diocletian and Constantine’s father. 

It is estimated that Christians probably only made up about 10% of the Empire’s population at the time of the battle. However, it had been growing rapidly over the last 50 years. Christianity may have only constituted 2 percent of the empire in the year 250.

Several histories of the period do mention Constantine having a dream, but others omit the story entirely. However, none of the original stories of the dream have it taking place the night before the battle. If it did happen, it probably happened in the months before the march to Rome. Likewise, the shields might have been painted much earlier as well, and with a cross, not a chi-rho.

There is an enormous amount of debate amongst historians regarding Constantine and Christianity. In particular, the very simple question of if Constantine was, in fact, a Christian himself. 

Much of what we know comes from a Greek Christian historian named Eusebius. Eusebius interviewed Constantine later in his life and wrote his biography, the Vita Constantini.

Eusebius makes note of Constantine’s dream in his biography but doesn’t link it to a particular time nor the battle of Milvian Bridge. 

As for Constantine, if he had converted to Christianity at this time, he had a funny way of showing it. Right after the battle, he marched into Rome and went directly to the Temple of Jupiter Capitolinus, which was the main pagan temple in the city. 

Today you can see for yourself the Arch of Constantine in Rome. Nowhere on it is there any mention of anything to do with Christianity. Likewise, official Roman coins and documents reference the Roman sun god for 12 years after the battle. 

So, if he was a Christian, he wasn’t in your face about it as emperor. Many think Constantine was probably influenced by his mother, Saint Helena. 

However, according to Eusebius, Helena didn’t convert to Christianity until after the Battle of the Milivian Bridge. 

It is widely assumed that he wasn’t baptized until near death, which was his get-out-of-jail-free card for all the sins he had committed, including murdering family members. 

He was baptized either by Eusebius or by Pope Sylvester I. However, the story of Pope Sylvester baptizing him might have been made up because Eusebius embraced the Arian heresy. Also, in the seventh century, it was part of a forged document called the Donation of Constantine, used to justify papal control over the City of Rome because supposedly Constantine had given it to the church in his will. 

So, Constantine’s personal religious beliefs are a major question mark, as is the veracity of the story of him seeing a cross in a dream.

What there isn’t any doubt about are the policies that Constantine implemented after he became emperor. 

A little over three months after the Battle of Milvian Bridge, Constantine issued the Edit of Milan, which gave Christianity formal tolerance of the empire and officially recognized freedom of religion. 

A copy of a letter sent to the governor of Bithynia in northern Turkey reported the edit by saying, 

When we, Constantine Augustus and Licinius Augustus, met so happily at Milan, and considered together all that concerned the interest and security of the State, we decided … to grant to Christians and to everybody the free power to follow the religion of their choice, in order that all that is divine in the heavens may be favorable and propitious towards all who are placed under our authority.

This did not make Christianity the official religion of the Roman Empire. That wouldn’t happen for another 67 years. 

The Christians were now allowed to practice their religion out in the open, which only accelerated the growth of the religion. 


In the years after the Edict of Milan, Constantine wasn’t neutral about Christianity. 

While at first he did actually encourage and fund the construction of Roman temples, by the end of his reign, he was pillaging them and tearing them down. 

Constantine was a patron of some of the Roman empire’s first churches. Before the Edict of Milan, most Christians secretly met in private homes. Constantine paid for the construction of these first buildings, including the original St. Peter’s Basilica in Rome, which I touched on in a previous episode. 

He also commissioned at least the first four churches in Constantinople. 


He also commissioned copies of the Bible, at least the gospels, for churches in Constantinople. 

He called the Council of Nicea in 325, which attempted to resolve the issue of Arianism, which held that Jesus was subordinate to God the father. It was probably the biggest issue facing the Christian community in the 4th century. 

So, you should be able to see why the Battle of Milvian Bridge was such as important battle. 

It was Constantine’s victory that allowed him to become emperor and allowed Christianity to move from becoming an underground, minority sect, to eventually becoming the official religion in the Roman Empire, the dominant religion in Europe, and was then spread around the globe to every continent. 

It was all due to a battle outside the walls of Rome, on the banks of the Tiber River, 1700 years ago. 


Everything Everywhere Daily is an Airwave Media Podcast. 

The executive producer is Darcy Adams.

The associate producers are Thor Thomsen and Peter Bennett.

Today’s review comes from listener HeatherIrene79 over at Apple Podcast in the United States. They write:

After 182 days of stuffing my brain full of knowledge, I am happy to report that I have completely caught up on this fabulous podcast. I’ve even been able to get my 9yo to listen to a few of the episodes that pertained to questions he asked me! I’m in the car a lot (Mom’s Taxi), so Gary has become my on-the-go teacher. Hoping to one day be able to go on one of the tours. So glad to have found this. Also a big thank you to Knox McCoy of The Popcast for making it a Green Light back in May! Hope that you have influenced a lot of people to tune in as well.

Thank you, HeatherIrene! I’d like to give you formal welcome to the completionist club. This month, everything in the club is flavored with pumpkin spice. Everything. 

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