Despite being some of the most powerful men in the ancient world, it can sometimes be hard to describe what exactly a Roman emperor did. While some are remembered for their tyranny, others are remembered for their philosophy. There was nevertheless a consistent expectation for the emperor to be a soldier. An emperor was expected to control the soldiers, protect the imperial borders, and vanquish Rome’s enemies. To be victorious was to achieve eternal renown. But for some, there would be no glory on the battlefield, only death…

A Dangerous Calling: Life and Death as a Roman Emperor

On the 1st of May, 305 CE, something extraordinary happened. The Roman emperor, Diocletian, weary after 21 years in power, announced his retirement. No longer would he be subjected to the intrigues and dangers of imperial rule. Instead, he would seek out a more serene final chapter. Combining the pastoral with the palatial, he retired to his vast residences at Salonae (Split, Croatia) to grow cabbages! Diocletian’s decision is especially striking because he was, and would remain, the only Roman emperor to voluntarily abdicate his power.

Throughout the centuries, from Augustus in 27 BCE through to Romulus Augustulus in 476 CE, to become emperor was to have a job for life. How long or short their reign was, depended on a whole host of different factors. Some emperors enjoyed long reigns and they would be remembered fondly long after their deaths. Many emperors were deified after death, joining the ranks of the gods and worshipped across the Empire. But, imperial politics was a dangerous game. Unable to maintain the careful balance of acceptance that legitimized their power, more often than not, emperors came to violent, bloody ends.

Emperors came to power with different ideas of what their role as the most powerful man in the ancient world was. Some, like Hadrian, were remembered for their cultural interests and as great builders. Despite this, every emperor needed to maintain a good relationship with the soldiers. Because the emperor lacked true legitimacy, power was maintained at the point of a sword. Each new ruler offered a large payment, or donative, to the soldiers upon his accession. Infamously, Tacitus records the advice of Mucianus to Vespasian that “anyone who is feared is noble enough.” For the new emperor, senatorial snobbery would be no concern — provided he had enough loyal legions to support his claim.

It was not just security that bound the emperor to the armies, however. The empire’s fighting forces also offered the chance for glory. Defeating Rome’s enemies and expanding the empire’s borders offered an emperor an enduring legacy: Trajan’s conquest of Dacia was an important factor in his being remembered as the optimus princeps. For those emperors who were successful in battle, triumphs could be celebrated in Rome, and grand monuments to their victories would be erected in cities around the empire. Not all emperors enjoyed military successes however…

1. Maximinus Thrax at the Siege of Aquileia

It was apt that Maximinus Thrax was killed in battle. For obscure origins in Thrace (hence, Thrax), Maximinus had been a soldier in the Roman army. Reputedly a giant of a man and improbably strong (though the Historia Augusta is far from trustworthy here…), his vigor made him popular with the men he fought alongside and he quickly rose through the ranks. Allegedly, he first came to prominence during the reign of Septimius Severus, and thereafter served the dynasty loyally. This was the case until 235 CE, anyway. During Severus Alexander’s Germanic campaigns, unrest among the soldiers grew, spurred on by distaste at the overbearing influence of Alexander’s mother, Julia Mammaea. Eventually, the men revolted. Led by Maximinus, Alexander and his mother were killed, and the Roman Empire had its first so-called “Barracks Emperor”.

Maximinus’ reign was brief but eventful. Wars were waged in Germany, as well as in Dacia and against the Sarmatians. His relationship with the senate was fractious, and a plot to trap him behind enemy lines in Germany was foiled early in Maximinus’ reign. A more serious revolt took place in North Africa in early 238. Disaffected landowners in Thysdrus rebelled and they killed corrupt officials and declared the elderly governor, Marcus Antonius Gordianus Sempronianus, and his son, as emperors. Gordian I and Gordian II were quickly supported by the Roman senate. Unfortunately, Capelianus, the governor of Numidia (and a long-term rival of Gordian and his son), mustered the legions and quashed the revolt before it could begin. Gordian II was killed in the fighting, and, in his grief, his father hung himself.

From his winter camp at Sirmium, Maximinus was furious at the senate’s treachery. Assembling his armies, he marched for Rome. However, on their way to the imperial capital, Maximinus and his army encountered unexpected resistance from the city of Aquileia. And a siege began. It soon became apparent that Aquileia had no intention of surrendering, with even women and children helping with the defence efforts. Herodian’s account of the siege includes a particularly gruesome description of what happened when the Aquileians poured pitch and olive oil on Maximinus’ men, burning them horribly, especially the poor souls trapped in wooden siege engines…

The soldiers grew increasingly disaffected with Maximinus’ inability to break the Aquileians, and in turn the emperor turned his wrath upon the soldiers. Rumors began to swirl around the camp that all Italy was united in arms against Maximinus, and fear and panic spread. A breaking point was reached in early May 238 CE, when a group of soldiers surprised Maximinus at his quarters. The emperor was slain, along with his son and heir, and their bodies mutilated, with the heads sent to Rome. There, they were greeted by an imperial triumvirate: the elderly senators, Pupienus and Balbinus, and the young man, Gordian III. The three of them make up the final rulers in 238, the year of the six emperors.

2. The Emperors Philip and Decius

During the middle decades of the third century, the Roman Empire experienced a series of crises. They were exacerbated by several military debacles. It was from one such disaster that Philip I emerged as emperor in 244 CE. His reign began with the death of Gordian III (in mysterious circumstances) on campaign against the Sassanian Empire. Sometimes called Philip the Arab as a result of his Syrian heritage, Philip decided to return to Rome quickly, to ensure that his accession had senatorial support. As emperor, Philip decided to spend big on celebrating his origins, spending lavishly on his hometown (renamed Philippopolis), and turning it into a place fit to be known as the birthplace of an emperor.

Philip’s reign incurred huge costs. There was the opulent expansion of his hometown and the vast expense needed to celebrate the Ludi Saeculares (the Secular Games) to celebrate Rome’s millennial anniversary in April 248 CE. More seriously, he had made a huge payment to the Sassanians to escape from Parthia, as well as the donative for the soldiers to secure his accession. Philip turned to increased taxation, and he also made the fateful decision to cease the payments made to the settlements north of the Danube.

Chaos quickly erupted on the imperial frontiers. A rebellion by the soldiers in Pannonia and Moesia was a catalyst for the tribes beyond the Danube to cross into the empire and ravage the provinces. Several other uprisings started around the empire and, although they never became too serious, Philip was soon overwhelmed. Despite attempts to resign, the Senate remained vocally supportive. In particular, Gaius Messius Quintus Decius so impressed Philip that he was given a special command to restore order in Pannonia and Moesia.

This was a poor decision. Decius’ successes prompted his soldiers to acclaim him emperor in 249 CE. Although he reputedly tried to negotiate with Philip, the two emperors met in battle near Verona. Philip’s forces far outnumbered Decius’, but confidence and discipline won the day. Philip was slain during the fighting, and Decius was now the sole emperor.

Decius’ own reign was no more successful than his predecessor’s. Hemmed in by invading Goths, religious tensions, and the emergence of the “Plague of Cyprian,” the two-year reign of Decius occurred during the worst ravages of the Third Century Crisis. Like Philip, he too was killed in combat. At the Battle of Abritus, first Decius’ son, and then the emperor himself, were killed. Although some traditions speculate that Decius fell due to a conspiracy orchestrated by his successor, the general Trebonianus Gallus, this seems unlikely. Instead, Decius became the first emperor to fall in battle against a foreign foe.

3. Maxentius at the Milvian Bridge

Diocletian had felt comfortable in retiring to his cabbage patch in 305 CE, partly because of the system he had put in place to rule the empire. To restore some semblance of stability to the empire, he established the Tetrarchy: the “Rule of Four.” Diocletian divided the empire into four sections and ruled with another senior colleague (an Augustus), and two junior colleagues (Caesars). Of course, rivalries soon erupted among Diocletian’s successors despite the division of power. By 311, the Tetrarchic system was very much in crisis and threatening to disintegrate. The main point of tension was between Maxentius and Constantine, and the two men vied for control of the western empire. Having declared war on his rival, Maxentius awaited the arrival of Constantine and his armies from the imperial capital where he had based himself.

By this point, the city of Rome lay behind the imposing defensive walls erected by Emperor Aurelian, so a siege would have likely proved difficult for Constantine and his armies. However, Maxentius opted to march out of Rome and meet his rival in battle. In 312 CE, the two armies drew up on either side of the Milvian Bridge, to the north of the city. The battle that took place is one of the most significant in world history. During the battle, Maxentius perished. Details of the battle are hazy at best, but it is thought likely that the emperor fell into the river and drowned, while around him the forces of Constantine overwhelmed his armies. Perhaps just as crucially, it was on the eve of this battle that Constantine reputedly had a divine vision and decided to have the Greek letters Chi and Rho emblazoned on this soldier’s shield. His vision had revealed to him that this sign, which symbolized Christ of the Christian faith, would guarantee victory: in hoc signo, vinces (“by this sign, conquer”). Whether true or not, Constantine’s victory over Maxentius at the Milvian Bridge ushered in Rome’s transformation into a Christian Empire.

4. Roman Emperor Valens and the Battle of Adrianople

The Gothic people who lived beyond the borders of the Roman Empire had long been a source of menace to the Roman emperors. Incursions were frequent, and occasionally these could degenerate into serious war. Even the most celebrated of emperors, such as Marcus Aurelius, found themselves struggling to reimpose Roman control, while others, like Decius above, actually lost their lives defending the empire’s frontiers. One of the most dramatic and consequential of these conflicts occurred late in the fourth century, during the reign of the emperor Valens (364-378 CE).

Valens, the ruler of the eastern empire based in Constantinople, oversaw a reign marked by several conflicts, both against the Goths to the north, and against the Persians to the east. In fact, it was Valens’ preoccupation with the latter that encouraged him to come to terms with the Goths during the First Gothic War (367-369 CE). The Second Gothic War, which began in 376 CE, would have a less successful conclusion for the emperor.

Pressure from the migrating Huns had displaced the Gothic people from their homeland and their leaders sought out permission from the Romans to cross the Danube and settle within the empire. Valens acquiesced, allowing the Gothic leader Fritigern to cross the river with his people. The sudden arrival of the Goths was initially a boon to Valens, as the new arrivals could be recruited into the Roman forces. However, relationships soon broke down when the newly arrived Goths began to rebel, and the situation rapidly deteriorated. Valens even sent word to Gratian, the emperor in the west, for support. Gratian sent soldiers to ensure that the Goths were contained where they were and did not spread into the rest of the empire.

Breaking off his campaign against the Persians, Valens hastened back to the empire, arriving in late May 378 CE. While Gratian’s advisors encouraged Valens to wait for the support of his counterpart in the West (who was detained in quashing violent unrest in Gaul), Valens listened instead to the urges of the people of Constantinople. He marched out to face the Goths. The two armies met near the city of Hadrianopolis in Thrace.

The Battle of Adrianople on the 9th August 378 was a catastrophic defeat for the Roman Empire, on a scale not seen for centuries. The historian, Ammianus Marcellinus, could think of nothing, save Rome’s near annihilation by the Carthaginians, as comparable: “The annals record no such massacre of a battle except one, at Cannae.” The historian gives two different accounts of the emperor’s fate, suggesting that he was either killed by an arrow, or that he was cut down and, after being carried to a small hut by his soldiers in a desperate bid to save him, he was burned inside by the Goths, unaware of the prize within… Regardless, the Gothic victory was crushing. Almost two-thirds of the Eastern Roman army lay dead on the field, including the emperor, whose body was never recovered. Although Valens would be deified, his legacy would forever be shaded by his defeat at Adrianople. The early 5th century historian Rufinus of Aquileia identified the massacre as the beginning of Rome’s terminal decline.

Valens would be the last Roman emperor to fall in battle until the emergence of the Byzantines, centered in Constantinople, which replaced Rome as the empire’s primary city. In the immediate aftermath of the debacle at Adrianople, imperial control would not be re-established in the region until the appointment of Theodosius as emperor in the east. For those emperors that followed the unlucky few to die in battle, their predecessors’ failures at least offered them the chance to seize glory for themselves.