Roman emperors were constantly afraid of assassination, usurpation, and rebellion, because the vast majority of them died by violence or were overthrown, not from natural causes. This fear was a rational response to a political system where the throne was won and held by military and political force, and where a swift, bloody death was the most common fate for a failed or unpopular ruler.
The Shadow of the Praetorian Guard
The Praetorian Guard, an elite unit originally created to protect the emperor and his family, became one of the most persistent threats to imperial life. They were the only armed force stationed permanently in Rome, and they quickly realized they could make or break emperors. They murdered Caligula in 41 AD, and then, after a brief, chaotic search, found his uncle Claudius hiding behind a curtain and proclaimed him emperor. In 193 AD, the Guard famously auctioned the throne to the highest bidder, Didius Julianus, after the murder of Pertinax. The Guard also killed Pertinax after only 87 days in power, because he tried to impose strict discipline and cut their pay. Emperors constantly had to manage the Guard with bribes and favors, but even then, the Guard could be swayed by a rival general who promised more. The fear was so acute that emperors like Septimius Severus, after seizing power in 193 AD, disbanded the old Guard and replaced it with loyal soldiers from his own legions.
The Constant Threat of Military Usurpers
The Roman Empire was a military autocracy, and the legions were the real kingmakers. Any general who commanded a large, loyal army was a potential rival. The so-called “Year of the Four Emperors” in 69 AD set the pattern: Galba, Otho, and Vitellius each seized the throne in quick succession, and each was murdered or executed by the next claimant’s forces. Vespasian, the fourth emperor that year, won by marching on Rome with his eastern legions. This was not an isolated event. In the third century, during the Crisis of the Third Century, there were at least 26 emperors in about 50 years, and most were killed by their own troops or by rivals. The threat was so pervasive that emperors often relied on trusted family members to command armies, and even then, a brother or son could turn on them. For example, Caracalla murdered his own brother Geta in 211 AD to be sole ruler, and was himself assassinated by a soldier in 217 AD.
Poison, Daggers, and Conspiracies in the Palace
The imperial palace was a hotbed of intrigue, and the most common instruments of death were poison and the dagger. Emperors were surrounded by senators, freedmen, servants, and family members who could easily slip poison into food or wine. The Roman historian Tacitus describes the murder of Claudius in 54 AD, allegedly poisoned by his wife Agrippina with a dish of mushrooms, so that her son Nero could succeed him. Nero himself was declared a public enemy by the Senate in 68 AD and committed suicide to avoid being executed. Domitian was assassinated in 96 AD in a palace conspiracy involving his own wife and several court officials. Even emperors who were not killed by poison lived in constant fear of it. They employed food tasters, and some, like the emperor Commodus, reportedly tested his own food on animals first. The fear of betrayal was so deep that emperors like Tiberius, who spent his last years on the island of Capri, rarely came to Rome and surrounded himself with a small, carefully vetted circle.
The Senate: A Source of Legitimacy and Danger
The Senate was a body of the Roman elite who had lost real power under the emperors, but who still held immense social prestige and could legitimize or condemn a ruler. Many emperors feared the Senate because senators often plotted against them, either to restore the Republic or to place their own candidate on the throne. Caligula was killed by officers of the Praetorian Guard, but the conspiracy was organized by senators, including the praetorian prefect Cassius Chaerea. Nero’s reign was marked by several senatorial conspiracies, most famously the Pisonian conspiracy of 65 AD, which aimed to kill him and replace him with the senator Gaius Calpurnius Piso. The conspiracy was discovered, and Nero executed or forced to suicide many senators and their families. Emperors often tried to maintain a working relationship with the Senate, but the mutual suspicion was never far from the surface. The emperor Trajan, who ruled from 98 to 117 AD, is often praised for his respectful treatment of the Senate, but even he kept a close watch on potential rivals.
The Danger of Popular Uprisings and Riots
While the military and the Senate were the most direct threats, emperors also feared the mob of Rome and the urban poor. Food shortages, high taxes, or perceived injustice could spark riots that threatened the emperor’s safety. The emperor Nero was widely believed to have started the Great Fire of Rome in 64 AD, and the rumor, combined with his unpopularity, led to a serious revolt in 68 AD. In 69 AD, the Roman people rioted against the emperor Vitellius, and he was killed by the mob in the streets of Rome. The emperor Aurelian, in the late third century, was assassinated by his own officers, but the trigger was a false rumor that he was about to execute them. The emperors often tried to appease the people with “bread and circuses”—free grain and spectacular games—but they knew that the mob could turn on them at any moment. The Roman historian Cassius Dio records that the emperor Commodus, who was extremely unpopular, was strangled by a wrestler in 192 AD, partly because the people had turned against him.
Fear of the Gods and Omens
Roman emperors also lived in fear of divine displeasure, which they believed could manifest as bad omens, eclipses, or unusual events. They were not just political leaders; they were also pontifex maximus, the chief priest of the Roman state religion. A bad omen, such as a comet, a lightning strike on the palace, or a statue that supposedly sweated blood, could be interpreted as a sign that the emperor was losing divine favor, which could embolden rivals. The emperor Nero reportedly panicked when a comet appeared, and he hired astrologers to predict his future. The emperor Domitian was obsessed with omens and prophecies, and he executed several people who were said to have predicted his death. The fear of omens was not just superstition; it was a political tool. Rivals could spread rumors of bad omens to undermine an emperor’s legitimacy. The emperor Julian, who ruled from 361 to 363 AD, was a pagan who tried to revive the old religion, and he was deeply concerned with the interpretation of omens before his fatal campaign against Persia.
Frequently Asked Questions
Were all Roman emperors murdered?
No, not all, but a significant majority were. Of the roughly 70 emperors who ruled from 27 BC to 476 AD, about 30 were assassinated, and many more were forced to commit suicide or died in battle. Some, like Augustus, Tiberius, and Vespasian, died of natural causes, but they were exceptions. The historian Suetonius, writing in the early second century, records that of the first 12 emperors, only 4 died of natural causes.
Why didn’t emperors just disband the Praetorian Guard?
They couldn’t. The Guard was a symbol of imperial power and a necessary protection against ordinary criminals and small-scale riots. Emperors like Septimius Severus replaced the Guard with loyal soldiers, but they still kept a bodyguard unit. The problem was that any bodyguard could turn on its master, and emperors had no other reliable armed force in the city. They tried to buy loyalty with pay and privileges, but that only made the Guard more powerful and more dangerous.
Did emperors really use poison tasters?
Yes, they did. The use of a praegustator, or food taster, is well documented. The emperor Claudius was killed by poison in mushrooms, despite having tasters, because the poison was placed in a particularly delicious mushroom that he ate before his taster could try it. After that, emperors became even more paranoid, and some, like Commodus, tested their food on animals first. The fear of poison was so great that some emperors, like Marcus Aurelius, reportedly took small doses of poison as an antidote, a practice known as mithridatism.
How did emperors protect themselves from assassination?
They used a combination of measures: they employed bodyguards, both the Praetorian Guard and personal Germanic or Spanish guards; they limited access to their person; they used informers to spy on potential conspirators; and they tried to keep the military and the Senate happy with gifts and honors. But no system was foolproof. The emperor Domitian was killed in his own bedroom by a freedman, and the emperor Caracalla was killed by a soldier while urinating on the side of the road.
Did the fear of assassination affect how emperors ruled?
Yes, it shaped imperial policy in many ways. Emperors often executed or exiled anyone they suspected of disloyalty, which created a climate of terror. They also spent enormous sums on the military and on public works to buy popularity. Some emperors, like Nero and Caligula, became increasingly erratic and cruel, possibly because of their fear, which only made them more hated and more likely to be killed. Others, like Augustus and Marcus Aurelius, managed to balance fear with effective governance, but they were rare exceptions.
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