When Rome Tore Itself Apart: 5 Crucial Events in the Civil Wars of the Tetrarchy

When Rome Tore Itself Apart: 5 Crucial Events in the Civil Wars of the Tetrarchy

Patrick Lynch - May 16, 2017

Rome had just recovered from the Crisis of the Third Century thanks to the relatively strong and stable leadership of Diocletian; although Aurelian deserves an immense amount of credit. Diocletian first became Emperor of Rome in 284 and defeated Carinus to become sole ruler in 285. He quickly realized that the vast size of the empire meant it was almost impossible for one man to rule effectively alone. He made Maximian his co-emperor (Augustus) in 286.

Not content with dividing the empire in two, in 293, Diocletian appointed Constantius and Galerius as junior co-emperors. In doing so, he created a tetrarchy of four leaders; two senior Augusti and a pair of lower ranking ‘Caesars.’ It appeared to be a good idea, at least in the short-term, as it made the empire much easier to govern. However, human nature, and the previous history of Rome suggested that having so many rulers was a recipe for disaster, and so it proved.

Harmony reigned until Diocletian fell ill at some point in 304 while on a campaign against the Carpi. There were rumors of his death soon after as he was not seen in public for months. When he finally emerged in March 305, he was emaciated and barely recognizable. The ancient historian Lactantius suggests that Galerius forced Diocletian to stand down in May 305; he was the first Roman Emperor ever to abdicate voluntarily.

Most people expected Constantine, son of Constantius, and Maxentius, son of Maximian, to become Caesars. Instead, the titles went to Maximinus Daia (Galerius’ nephew) and Severus. Maximian also abdicated his throne and was replaced by Galerius, Constantius became the new co-emperor in place of Diocletian, and all hell was about to break loose.

When Rome Tore Itself Apart: 5 Crucial Events in the Civil Wars of the Tetrarchy
Diocletian. Ancient History Encyclopedia

1 – Maxentius the Usurper Grabs Power in Rome

Tensions were already bubbling under the surface, but perhaps disaster could have been averted had both new emperors reigned for as long as the previous duo. However, Constantius died just a year after becoming co-emperor (he ruled in the West) and was succeeded by Severus. This immediately caused a problem because Constantine was originally expected to be Caesar so when his father died; his troops rallied behind Constantine and declared him Augustus.

If matters were not complicated enough, Maxentius, also overlooked as a Caesar in 305, was unhappy at being left out of the equation. Emperor Galerius reluctantly bestowed the title ‘Caesar’ upon Constantine and sent him the purple robes of monarchy, which were readily accepted by Constantine as a symbol of his legitimacy. This caused Maxentius to act, and he declared himself Emperor of Rome in 306 in place of Severus.

Galerius was worried that this power grab would encourage others to come after his throne; so he ordered Severus to deal with the threat. Severus marched towards Rome with an army that was once led by the usurper’s father and former emperor, Maximian. The anxious Maxentius offered his father the position of co-emperor which the ex-leader gleefully accepted. Once Severus arrived in Rome, he was horrified to find that his men defected to their old commander. He fled to Ravenna to an untouchable position but foolishly believed Maxentius’ promise that he would spare his rival’s life if he surrendered.

Severus surrendered in March/April 307 but was immediately taken captive, imprisoned and eventually executed. After hearing the news, Galerius decided to march towards Rome himself and took a huge army with him. Remarkably, Maxentius was able to replicate what he did with Severus to a degree. A significant number of Galerius’ army defected after the promise of wealth and out of respect for Maximian. Galerius withdrew but angrily looted as much of Italy as he could along the way. By now, Maxentius had control of Italy and Africa and looked to consolidate power by making friends with Constantine.

Constantine married Maxentius’ daughter and received the co-emperor title from the senior ruler. Constantine was not willing to rise against Galerius. In April 308, Maximian attempted to depose his son but was shocked as the men remained behind the new ruler, so he fled to Constantine. Several of claimants to the throne called a conference at Carnuntum in 308 to try and salvage the situation. They begged Diocletian, who was in attendance, to return to power but the ex-emperor refused because he was happier farming cabbage than he was ruling an empire. He ordered Maximian to step down, decreed that Maxentius was no longer emperor and installed Licinius as the new leader.

The ‘compromise’ satisfied no one, and soon after the conference, all the claimants were at war against one another. Maximian had no intention of ‘retiring’ and rebelled against Constantine. He declared himself emperor by donning the imperial purple at the town of Arles and claiming that Constantine was dead. However, his attempts to bribe his new rival’s men failed, and soon, he left Arles. An irate Constantine returned from his campaign against the Franks to confront Maximian at Massilia. The luckless former Emperor was betrayed by the citizens of the city and stripped of his title. While Constantine showed clemency, he reportedly encouraged Maximian to commit suicide, and the three-time emperor did so in July 310 by hanging himself.

When Rome Tore Itself Apart: 5 Crucial Events in the Civil Wars of the Tetrarchy
Maximinus Daia. Wikimedia

2 – Maxentius Consolidates

At the conference at Carnuntum, everyone in attendance agreed that Maxentius was a usurper with no justifiable claim to power. As a result, he was a marked man and could not call on any of the others as an ally. He suffered a blow in 308 when he lost the province of Africa. There, the troops rallied behind Alexander of Carthage and declared him Augustus of the province. Africa was effectively the ‘breadbasket’ of Rome, and it also meant that Alexander became an ally of Constantine’s through virtue of the fact they had an enemy in common.

Maxentius’ eldest son died in 309, and once Maximian died the following year, the relationship between Maxentius and Constantine quickly deteriorated. As a result, Maxentius formed an alliance with Maximinus Daia, but in 310, he lost Istria to Licinius. If things weren’t unstable enough already, Galerius fell ill and died in April 311. His death was the catalyst for an all-out civil war all across the vast Roman Empire.

As soon as Maximinus heard of Galerius’ death, he raised an army against Licinius and seized Asia Minor before his enemy could act. Maxentius got to work by strengthening his position in northern Italy before traveling to Africa to kill Alexander in 310/311. He seized the wealth of Alexander’s supporters in Africa and ensured Rome was flooded with grain. Despite his best efforts, Maxentius was never able to garner support and was soon forced to bring taxation back to Rome to gain extra revenue as he received nothing from the empire.

Although he tried to get Italy’s Christians on his side by allowing them to elect a Bishop of Rome, they sided with Constantine in the belief that he was more sympathetic to their needs. By the summer of 311, Maxentius had raised an army to fight Constantine while Licinius was busy in the east of the empire. For his part, Constantine quickly saw the danger and formed an alliance with Licinius by letting the man marry his sister Constantina. By the start of 312, two clear sides had formed; an alliance of Constantine and Licinius and an alliance of Maxentius and Maximinus Daia.

When Rome Tore Itself Apart: 5 Crucial Events in the Civil Wars of the Tetrarchy
Statue of Maxentius. Ancientromeeu

3 – Constantine Defeats Maxentius at the Battle of Milvian Bridge

During the winter of 311/12, Constantine remained at Colmar and commanded an army of approximately 100,000 men. However, he needed a significant number of them to guard the Rhine, so his ‘field army’ was probably no more than 25,000 troops. However, his army was augmented by thousands of hardened veterans received from Germans and Gauls. Maxentius was waiting for him in Italy with a far larger force.

Constantine marched to Italy and immediately encountered resistance at Segusium as the city closed its gates when he arrived. Unperturbed, Constantine attacked, set the gates on fire and his troops scaled the walls and quickly took the city. He did not allow his men to plunder and they marched onward to modern day Turin where they faced a large force of Maxentius’ cavalry. He cleverly spread his men in a line and allowed the enemy to charge into the middle. His cavalry charged the enemy at the sides and knocked them off their horses with blows from iron-tipped clubs. The people of Turin refused to give Maxentius’ men sanctuary and opened their gates to Constantine.

Word spread quickly throughout northern Italy that Constantine’s army was gaining impressive victories and showing mercy to towns that opened their gates. Perhaps his refusal to plunder Segusium helped his cause. In any case, several more towns welcomed the invading would-be emperor, and when he reached Milan, he found the city had its gates open for him, and the people welcomed him and his men with cheers. Constantine took advantage of the warm reception by staying in Milan until the summer of 312.

Previously, Maxentius enjoyed success by remaining in Rome, allowing his enemies to come to him and holding out until they ran out of resources and withdrew. While hindsight is always 20-20, perhaps he should have continued a winning strategy. Instead, he abandoned the plan and elected to leave Rome to meet Constantine in open battle. He apparently consulted the Sibylline Books which said ‘on October 28 an enemy of the Romans will perish.’ Constantine left Milan and defeated armies at Brescia and Verona before meeting Maxentius near Milvian Bridge.

Constantine apparently had a vision the night before the battle where he saw the symbol of Christ, the ‘Chi-Ro,’ shining above the sun. He believed it was a divine sign and ordered his men to paint the symbol on their shields. On October 27, Maxentius was at a chariot race, and the crowd openly taunted him by saying Constantine was invincible. He built a temporary wooden bridge across the River Tiber to prepare for a battle with his enemy as he destroyed part of the main bridge when preparing for a siege; it was a fatal error.

On the morning of October 28, 312, the Battle of Milvian Bridge took place. It was one of the most important victories in the history of the Roman Empire as it changed its course completely. Constantine was delighted to meet his enemy in open battle as his forces were down to around 30,000 men (although figures vary according to the source) and he did not want to lose resources in a siege on Rome. Maxentius has a significant numerical advantage by all accounts but could not match his enemy’s skill in battle.

Maxentius deployed his men in a long line with their backs to the Tiber and Constantine matched him to avoid getting outflanked. Maxentius probably placed his men too close to the river, and when Constantine’s cavalry attacked, Maxentius’ cavalry broke and became very disorganized. Constantine seized the initiative by charging with his infantry and pushing his enemy’s troops into the Tiber where many of them drowned. Some sources suggest Maxentius’ men tried to flee across the temporary bridge only for it to collapse. Regardless of what happened, the battle was brief, and Maxentius drowned in the Tiber.

Constantine’s men found the washed up body, decapitated it and put in on display in Rome. Later, the head was sent to Carthage as a warning; it proved effective as the Africans offered no further resistance. Constantine was now sole emperor of Rome in the West, and he ordered the death of Maxentius’ entire family and closest friends but refused to order a wide scale massacre. Romans hoping for a return to its glory days were disappointed as Constantine taxed the citizens, tried to abolish the Circus games and disbanded the Praetorian Guard. Within a couple of months, Constantine left Rome as the civil war was far from over.

When Rome Tore Itself Apart: 5 Crucial Events in the Civil Wars of the Tetrarchy
Emperor Licinius. Pinterest

4 – And Then There Were Two: Licinius Defeats Maximinus Daia

Licinius took Galerius’ Balkan territories soon after the death of the emperor but was unable to prevent Maximinus from taking important territories in Asia Minor. The two men came to an uneasy truce whereby the Bosporus became the border between their lands. Constantine’s decisive victory completely changed things because now, both men knew they had beat the other to gain a level of power equal to that of Constantine.

Licinius wisely continued to remain on friendly terms with Constantine when he confirmed the emperor’s Edict of Milan in 313 (in June) which ordered tolerance of Christians; Licinius also agreed that Constantine was the ‘senior’ Augustus. In early 313, Maximinus crossed the Bosporus with an army and landed in Thrace. It was a disastrous move because his troops were exhausted from crossing the mountains of Asia Minor in winter. Nonetheless, he continued marching onward and took Heraclea after a short siege.

Meanwhile, Licinius arrived at Adrianople while his enemy was still attacking Heraclea. Maximinus moved to the ‘first station’ some 18 miles from the town and was told that Licinius had camped in the ‘second station’ which was 18 miles from Maximinus’ current location. The two would-be emperors engaged in negotiations which proved fruitless so on April 30, 313, the two armies met at the Battle of Tzirallum.

On the surface, Maximinus held all the aces; he had 70,000 men against Licinius’ 30,000 and his troops included seasoned veterans from the Asiatic provinces. Initially, the numerical advantage gave Maximinus the advantage but soon, Licinius’ superior tactical ability helped him gain the upper hand, and after a few hours, he completely routed the enemy and attained a decisive victory.

Maximinus fled the battlefield with remarkable speed and was apparently 160 miles away at Nicomedia within 24 hours of his defeat. Ancient sources suggest the defeat broke him as he was seen trembling and pale and was not wearing his imperial robes. Although Licinius bided his time, he eventually pursued his enemy in the hope of earning a crushing win to end the conflict. Licinius marched on Tarsus where he laid siege to his enemy. Maximinus either committed suicide by drinking poison or died from illness in August 313.

Licinius gained all of Maximinus’ territories so, at this stage, the complicated nature of the civil war had ended. The empire was divided amongst two men with Licinius ruling the east and Constantine in charge of the west. Everything east of Pannonia belonged to Licinius while Constantine ruled everything west of Italy. At this point, the two emperors could have reigned side by side peacefully but as this is ancient Rome we’re talking about, trouble was never far away.

When Rome Tore Itself Apart: 5 Crucial Events in the Civil Wars of the Tetrarchy
Constantine the Great’s Statue. Pinterest

5 – Constantine Becomes Sole Emperor

The accord between the two emperors didn’t last long. Constantine appointed Bassianus, his brother-in-law, as Caesar, with authority in the Danubian provinces and Italy. Licinius saw Bassianus as a puppet and was angry that such a man could take control of his military provinces in the Balkans. He persuaded Bassianus to rebel against Constantine in 314 or 315 but not only did his enemy easily suppress the revolt, he knew Licinius was involved, and the relationship between the two men broke down.

They both took time out to prepare their respective armies, but in 316, they fought in Pannonia where Constantine emerged victorious despite a numerical disadvantage. Licinius decided to name Aurelius Valerius Valens as the new emperor of the west; a failed attempt to undermine the authority of his rival. After an indecisive battle in Thrace, the two men signed a treaty in 317 at Serdica.

Licinius agreed to surrender all Balkan and Danubian provinces to Constantine barring Thrace but retained control over his remaining eastern territories. He also agreed to execute Valens. Finally, they agreed to name three new Caesars; Licinius the Younger (Licinius’ son) and two of Constantine’s sons, Constantine II and Crispus. The empire enjoyed a short spell of peace, but war broke out again when Licinius started persecuting Christians in 320. In defiance of the treaty at Serdica, Licinius appointed himself and two of his sons as consuls in 322. Constantine responded by appointing his son Constantius II as consul in 323.

In the same year, he broke the agreement by marching on Licinius’ Thracian territory, and his enemy declared war in 324. Constantine quickly gained the advantage with victory at Adrianople followed by a major naval victory. Licinius retreated to Asia Minor and was pursued by his enemy. Constantine won another important battle at the Hellespont before the two emperors fought one last time at the pivotal Battle of Chrysopolis on September 18, 324.

Constantine arrived at the battlefield first and retired to his tent to seek divine guidance. He emerged and decided to take the initiative and launch an attack when his enemy came into range. The religious element of the battle was apparent as Constantine’s men marched under his Christian standard (the Labarum) while Licinius’s troops displayed images of Rome’s pagan gods. Licinius apparently feared the labarum and wouldn’t allow his men to attack it or even look at it directly.

While Constantine often liked to employ clever strategy during his battles, Chrysopolis was different. He decided to launch a huge full frontal assault at the enemy in what was an incredibly successful move. Licinius’ army fell apart and was routed. According to one ancient historian, Zosimus, Licinius lost up to 30,000 men in the battle. He fled and later agreed to surrender, but after a few months in captivity, he was executed while his son was murdered the following year.

Constantine the Great was now the sole ruler of the entire Roman Empire and ensured that Christianity became the empire’s religion by banning pagan sacrifices in 324. Pagan temple treasures were confiscated and used to pay for the creation of Christian churches. He outlawed gladiatorial games and issued harsh punishments for ‘sexual immorality.’ Crucially, Constantine decided to move the empire’s capital from Rome to the site of Byzantium in the eastern part of the empire. He built the city beginning in 324 and consecrated it in 330. Constantinople became one of the greatest cities on earth and thrived while Rome was soon sacked and conquered.