Cold Open

It’s July 324 CE, off the coast of Asia Minor, now known as Turkey.

Wind whips through the air as Flavius Julius Crispus grips the rail of his ship.

Waves thump against the hull, but there’s no turning back. Crispus knows that he must ignore the risk of capsizing and advance into the choppy waters if he is to have any chance of victory over the enemy.

The Roman Empire has slipped into civil war, with rival leaders vying for power. Crispus fights for his father, Constantine. And today he’s facing the navy of Constantine's adversary, Licinius. Crispus must break through if his father is going to conquer Licinius’s stronghold in the eastern provinces.

But as Crispus pushes his ship on, an enemy vessel suddenly emerges through the spray. It’s nearly twice the size of Crispus’s ship, but it’s far slower—and that gives Crispus an opportunity.

He barks out orders and feels the deck beneath him shudder as the ship turns sharply.

Crispus unsheathes his sword, and dozens of other soldiers on deck follow suit.

He silently counts down the last few yards until eventually...the two ships collide, and a pitched battle erupts in the middle of the churning sea.

By exploiting the stormy waters, Flavius Julius Crispus will shatter the enemy fleet. The civil war in the Roman Empire won’t end there, but victory at the Battle of the Hellespont will clear the path for Crispus’s father, Constantine, to march on, setting up a final, decisive battle at Chrysopolis on September 18th, 324 CE.

Introduction

From Noiser and Airship, I’m Lindsay Graham, and this is History Daily.

History is made every day. On this podcast—every day—we tell the true stories of the people and events that shaped our world.

Today is September 18th, 324 CE: The Battle of Chrysopolis.

Act One: Constantine, from soldier to ruler

It’s spring 303 CE, just outside the city of Nicomedia in the Eastern Roman Empire, 21 years before the Battle of the Hellespont.

Constantine rides toward the city at the head of his elite cavalry unit. His horse kicks up dust as a palace comes into view. After several years campaigning on the Roman Empire’s frontiers, the 30-year-old Constantine is looking forward to a break from war and to all the comforts reserved for a nobleman of his rank.

But a commotion at the side of the road catches his eye. A cluster of travelers huddles just off the highway, their wrists bound and eyes downcast. Soldiers rifle through their cart, emptying sacks and chests searching for something. As Constantine draws nearer, one of the rummaging soldiers shouts in triumph. He lifts a gold cross from a sack, and it glistens in the sunlight. The travelers’ heads sink, knowing that their fate is sealed. The soldier has just found proof that they are Christians.

At the turn of the 4th century, no religion in the Roman Empire is growing faster than Christianity. Although its various sects differ in their practices, they all share one core belief: that there is only one God. This puts them at odds with the traditions of the Roman Empire, where worshiping many gods is the norm. And while some emperors have tolerated Christians, treating their God as just another deity among hundreds. Other rulers have been more suspicious—and now, it seems that the Christians are being targeted by the authorities once again.

Constantine reins in his horse as he approaches the Christians at the side of the road. Most glare at him with undisguised resentment. But one woman meets his gaze, eyes pleading, and begging for help. Constantine hesitates, unsure what to do. As far as he’s concerned, the Christians have done nothing wrong and don’t deserve to be persecuted. But he doesn’t feel he can get involved before he knows more about what’s happening here. So, Constantine just tightens his jaw and rides on, leaving the woman and her companions to their fate.

A few minutes later, Constantine reaches the palace. There, he learns that the soldiers outside were acting on the orders of Emperor Diocletian himself. He has commanded his men to destroy Christian dwellings, burn scriptures, and seize artifacts. But although Constantine is troubled by this latest bout of persecution, he decides he has no right to intervene on the road. If it is an imperial order, there is nothing he can do. Speaking out would only cause trouble, not just for himself, but also for his father—and that could be catastrophic for the entire empire.

Seventeen years ago, Emperor Diocletian radically overhauled the governance of the Roman world. Managing Rome’s vast territories had become seemingly impossible for one man alone. So, Diocletian split the empire in two, appointing a co-emperor to rule in the West, while he ruled in the East. Soon after, he added two junior emperors to lighten the administrative load even further. This system is known as the “Tetrarchy”, and right now, Constantine's father is the junior emperor in the West. That makes him an important figure—and puts Constantine on guard. He doesn’t want to make life difficult for his father by doing anything rash.

Still, in the tumultuous Roman Empire, no one ever has a secure grip on the throne, and two years later, the delicate power-sharing agreement is put to the test. In May 305 CE, Diocletian falls ill and retires from his position as ruler of the Eastern Empire. But now that there are multiple emperors, there is no obvious line of succession, and within weeks, Diocletian’s absence sets up a struggle for power. Constantine's father emerges as the senior emperor in the West, and army General Galerius takes over in the East. But that leaves Constantine feeling vulnerable. He hears whispers that Galerius considers him a potential rival.

Fearing assassination, Constantine decides to escape the court of Galerius and join his father in the West. So one night, when Galerius is drinking heavily in the palace, Constantine secretly saddles a horse and gallops away before anyone can stop him. He flees west, riding as fast as he can, pausing only to snatch a few hours of sleep at the homes of trusted allies. Eventually, Constantine reaches the safety of his father’s court in the distant province of Britain.

Father and son spend the next year fighting on the remote northern frontier of the empire, until July 306 CE, when Constantine's father is killed in battle. His father's soldiers immediately proclaim Constantine as the new Emperor in the West. But not everyone will accept Constantine's claim to the throne. His legitimacy will soon be challenged, and his armies will be forced to march again, fighting their fellow Romans. And the prize will be ultimate power.

Act Two: Constantine fights for sole rule

It’s October 29th, 312 CE, near Rome, six years after Constantine was proclaimed the Western Roman Emperor.

Constantine rides at the head of his troops toward the Milvian Bridge, an important crossing point on the River Tiber, just north of Rome. Wearing heavy armor, he steadies himself and looks to each side, taking in his column of soldiers. They are weary from a lack of sleep, but their heads are held high, and Constantine sees in their eyes a fiery belief that they will win a decisive victory today.

For the past year, Constantine has been waging a war against a rival named Maxentius. A few months ago, Constantine marched his men through the Alps and moved south through Italy. One by one, cities fell to his army, and Maxentius was forced to retreat farther south. But Maxentius has been able to hold on to power thanks to his control of Rome. Now, though, both men know that the next battle will be decisive—because it will decide who rules the empire’s capital.

But despite his soldier’s bravado, the odds seem to be against Constantine. Maxentius's men outnumber his two to one. Maxentius also had time to dig defensive earthworks and stockpile weapons and supplies, while Constantine’s army is tired from weeks on the road.

Still, Constantine shows no hesitation—because he claims he’s received a sign of divine favor.

Last night, Constantine tossed and turned as dreams interrupted his sleep. When he woke in the early hours, he said he could clearly remember one vivid vision. In the sky, blazing in sunlight, Constantine had seen a symbol commonly used by Christians: the first two Greek letters in the word “Christ,” superimposed on one another to make a cross-like pictogram. Although he is not a Christian, Constantine felt compelled to adopt the symbol. To him, it was clearly a sign from the heavens. So, he ordered his troops to be woken before dawn to give them time to daub their shields with the new design. Now, as they line up to await orders, Constantine can see the freshly painted sigil glinting in the sunlight.

Confident that his troops are protected by divine favor, Constantine orders his cavalry to charge. The first column breaks through the enemy lines, forcing Maxentius's troops back toward the Milvian Bridge. Discipline breaks down as Maxentius's soldiers flee for their lives. And although most cannot swim, many jump into the river in their desperation to escape. Even Maxentius himself ends up in the water, and his fate is the same as his soldiers—drowned under the weight of his armor.

Once victory is certain and the last enemy fighters are captured or killed, Constantine orders Maxentius's body to be pulled from the river. There, on the banks of the Tiber, Maxentius is posthumously decapitated. And only hours later, Constantine's army marches into Rome, parading the head through the streets.

Then, the Roman Senate declares that Constantine is the rightful emperor, finally cementing his authority over the Western Empire.

From his new seat of power in Rome, Constantine becomes convinced that it was the Christian God who carried him to victory. And he believes that he has been given a mission to expand the Christian faith throughout the Empire.

Still, Constantine is politically astute enough not to force the issue. He knows that the majority of his citizens are not Christian, and he is careful not to persecute them. Instead, Constantine allows the two religions to coexist, using symbols and imagery from both Roman traditions and Christianity, and refusing to publicly reveal his own personal faith. This way, all citizens of the West can claim him as one of their own—and peace can reign.

But the same cannot be said of the other half of the Roman Empire. In the East, persecution of Christians continues in many regions. So, the year after the Battle of the Milvian Bridge, Constantine meets with his counterpart, the new Eastern Emperor Licinius, to hammer out an agreement.

The result of their talks is the Edict of Milan. It repudiates the policies of the old emperor Diocletian and grants Christians new legal protections that officially recognize their faith as a legitimate religion throughout the empire.

A new age of harmony and tolerance seems within reach. But only seven years later, in 320 CE, Licinius will go back on his word and resume his attacks on Christians. This will spur Constantine into one last military campaign to seize absolute control over the Roman Empire and end the power-sharing Tetrarchy once and for all.

Act Three: Battle of Chrysopolis

It’s dawn on September 18th, 324 CE in Chrysopolis, twelve years after the Battle of the Milvian Bridge.

Emperor Constantine emerges from his tent as the first light of day spills across camp. Waiting for him are his top military officers, each expecting orders for the upcoming battle. But Constantine’s gaze fixes on the horizon, where the ranks of Licinius’s army stretch out in an unbroken line. Then, without a word, Constantine turns and disappears back inside his tent. There, he drops to his knees and begins to pray.

A few days earlier, a messenger arrived at Constantine's camp with news of an important victory: his eldest son, Flavius Julius Crispus, had defeated Licinius’s navy in the Hellespont. The sea now lay open, clearing Constantine's path to the east, where the bulk of Licinius’s army can be found. Constantine ordered his troops to march—and now, they’re within striking distance of Licinius’s troops at Chrysopolis.

Slowly, Constantine rises from one knee after he finishes praying. Then, he orders a direct assault on Licinius’s army. The fighting is brutal and unrelenting. Constantine's soldiers have the advantage of the higher terrain, but Licinius refuses to yield, and he sends unit after unit into the breaches in his line. The battlefield is soon littered with the dead and dying. And by the time the fighting ends, more than 25,000 of Licinius’s soldiers have fallen. Yet Licinius himself escapes and rallies his remaining forces in the city of Nicomedia.

But rather than prolong the bloodshed, Constantine sends his sister to broker peace. Eventually, Licinius agrees to relinquish power in exchange for his life, and Constantine becomes emperor of both the Western and Eastern Roman Empire. With his enemies crushed and ultimate power in his hands, Constantine is ruthless. He reneges on the deal he struck with his defeated enemy, and Licinius is put to death.

With no one left to challenge his authority, Constantine becomes the first Roman emperor in decades to rule alone. He will use his power to make sweeping changes, moving the capital from Rome to a new city he names after himself: Constantinople. And from his new palace there, he will actively promote the Christian religion, fostering the rapid growth of the faith across the empire. By the time Constantine dies in 337 CE, Christianity will have transformed from a fringe cult to a mainstream faith, having been given a crucial foothold by Constantine’s victory at the Battle of Chrysopolis on September 18th, 324 CE.

Outro

Next on History Daily. September 19th, 1868. White supremacists attack a peaceful march protesting the expulsion of Black politicians from the Georgia state legislature.

From Noiser and Airship, this is History Daily, hosted, edited, and executive produced by me, Lindsay Graham.

Audio editing by Muhammad Shahzaib.

Sound design by Mollie Baack.

Music by Thrumm.

This episode is written and researched by Dorian Merina.

Edited by Scott Reeves.

Managing producer Emily Burke.

Executive Producers are William Simpson for Airship and Pascal Hughes for Noiser.