Caligula: The Roman Emperor Who Declared Himself a God

The Making of a Monster

Gaius Julius Caesar Germanicus — known to history by his nickname Caligula, meaning "little boots," given to him by his father's soldiers when he was a child — was born in 12AD, the son of the popular general Germanicus and the great-granddaughter of the Emperor Augustus. His early years were marked by tragedy: his father died under suspicious circumstances in 19AD, his mother and two brothers were imprisoned and killed by the Emperor Tiberius, and Caligula himself spent years effectively as a hostage at Tiberius's court on the island of Capri.

The ancient historian Suetonius writes that Tiberius, watching the young Caligula closely, once remarked that he was "nursing a viper for the Roman people." What we know of Caligula's character during these years is difficult to assess — ancient sources are almost uniformly hostile, and the accounts of his behaviour at court were written by people with strong incentives to paint him as monstrous.

When Tiberius died in 37AD — possibly with Caligula's assistance, though this cannot be verified — Caligula succeeded him as emperor at the age of 24. The early months of his reign were celebrated across the empire. He released political prisoners, abolished the treason trials that had terrorised the Roman upper classes under Tiberius, and staged spectacular games and public entertainment. The Senate adored him. The people adored him.

The Descent

Approximately six months into his reign, Caligula fell seriously ill. When he recovered, something had changed. Ancient sources describe a man who was increasingly erratic, cruel and megalomaniacal. He began executing people without trial or clear cause, including close family members. He declared himself a living god — identifying himself with Jupiter and other deities — and reportedly had a temple built to himself. He demanded that his statue be placed in the Temple in Jerusalem, a demand that would have provoked a Jewish uprising and was only averted by the intercession of the governor Petronius and, ultimately, Caligula's death.

The stories that have made Caligula famous — and infamous — date from this period. According to Suetonius, he made his favourite horse, Incitatus, a priest and intended to make him a consul. He reportedly committed incest with his sisters. He forced senators' wives to work as prostitutes. He executed men for trivial offences, reportedly including for not being adequately enthusiastic about his performances as a singer or dancer.

How much of this is literally true is impossible to determine. The horse story may have been a deliberate provocation — Caligula demonstrating his contempt for the Senate by suggesting even a horse could do their job. The incest allegations were a standard form of political slander in the ancient world. The general picture of a cruel, erratic and dangerous ruler is probably accurate; the specific anecdotes may be exaggerated or invented.

The Assassination

Caligula's reign ended on January 24th, 41AD — exactly four years after it had begun. A conspiracy organised by officers of the Praetorian Guard, led by Cassius Chaerea, stabbed the emperor in a palace corridor. He was struck thirty times. His wife and infant daughter were also killed. He was 28 years old.

The Senate briefly discussed restoring the Republic. The Praetorian Guard, however, discovered Caligula's uncle Claudius hiding behind a curtain in the palace — reportedly in terror — and acclaimed him emperor instead. The Republic, as in the aftermath of Julius Caesar's assassination a century earlier, proved impossible to restore. The empire was too entrenched, and too many people depended on it for their income and power.

Power and Its Corruption

Caligula's reign raises questions that resonate far beyond ancient Rome. How does unchecked power change a person? Can the brutality of Caligula's early years — watching his family destroyed by imperial power, living in fear at Tiberius's court — explain his later behaviour? Or was the explanation simpler: that the Roman imperial system gave one person absolute power over millions, with no meaningful checks or accountability, and that very few humans could exercise such power without it corrupting them?

The political philosopher Lord Acton's famous observation — "power tends to corrupt, and absolute power corrupts absolutely" — finds one of its most vivid illustrations in the reign of Caligula. Whether he was truly the monster ancient sources describe, or simply a young man damaged by trauma who found himself with unlimited power, the result was the same: a reign of fear and violence that ended only when those closest to power decided they had had enough.

For more on political power and corruption in Rome, see our articles on Julius Caesar and the Fall of the Roman Empire.

Before the Tyranny: The Early Reign

Gaius Julius Caesar Augustus Germanicus — known as Caligula, a childhood nickname meaning "little boot" given by the soldiers in his father Germanicus's army — became emperor in 37 CE at the age of twenty-four. His accession was greeted with enormous popular enthusiasm. Tiberius, his predecessor, had been a withdrawn and increasingly paranoid ruler whose later years were marked by terror, treason trials, and rumoured debaucheries on Capri. The young Caligula, son of the popular general Germanicus, seemed to promise a fresh start.

The first seven months of his reign appeared to justify this optimism. He recalled political exiles, ended treason trials, destroyed the records that had been used against those accused under Tiberius, and made gestures of goodwill toward both the Senate and the people of Rome. The historian Suetonius recorded that the Roman people "adored" him.

The Illness and the Transformation

In October 37 CE, Caligula fell seriously ill — ill enough that his life was feared for. When he recovered, he was a changed man. Whether the illness itself caused a neurological change, whether the experience of near-death transformed his personality, or whether the initial moderate period had simply been a calculated performance that he chose to abandon after consolidating power, is impossible to determine from the surviving sources.

What is clear is that after his recovery, Caligula's behaviour became increasingly erratic and cruel. He began executing members of his own family, then senators, then others. He demanded divine honours, reportedly declaring himself a living god and establishing a temple to his own genius. He appeared in public dressed as various deities — Jupiter, Mercury, Venus, Hercules. He is said to have appointed his horse, Incitatus, to the consulship, though this story may be ancient satire rather than literal fact.

The Problem of the Sources

The historical Caligula is extremely difficult to recover because the surviving sources — Suetonius, Cassius Dio, Philo of Alexandria — were written decades or centuries after his death and reflect the perspectives of those he alienated or oppressed: the senatorial class. The ancient "biography" genre, particularly in Suetonius, collected scandalous anecdotes without much concern for verification.

Modern historians have approached Caligula with considerable scepticism about the worst stories. The horse-consul anecdote, for instance, is probably best understood as Caligula's contemptuous joke at the expense of the Senate — a way of saying that a horse was as worthy of their dignities as they were — rather than a literal appointment. The stories of incest with his sisters may be hostile invention or exaggeration. Even the stories of random murders may be selective rather than representative.

What does seem clear is that Caligula was a genuinely difficult ruler who executed significant numbers of people, engaged in behaviours that the senatorial class found outrageous and humiliating, and proved impossible to manage through the normal informal mechanisms of imperial politics. Whether he was clinically insane, deliberately provocative, or simply a young man who had grown up in a dysfunctional imperial family and had never developed normal social boundaries is a question that cannot be definitively answered.

The Assassination

Caligula was assassinated on 24 January 41 CE by officers of the Praetorian Guard, in a conspiracy that also involved members of the Senate. The conspirators stabbed him repeatedly — some accounts say thirty times — in a colonnade of the palace complex. His wife and infant daughter were killed the same day.

The Praetorian Guard then discovered his uncle Claudius hiding behind a curtain and proclaimed him emperor — an event that demonstrated, inadvertently, how completely the republican institutions of Rome had been hollowed out. The Senate briefly contemplated restoring the republic before accepting the reality that the army's choice would prevail.

Claudius proved a considerably more effective ruler than his nephew, which made Caligula's short reign seem even more wasteful in retrospect. The four years of Caligula's rule cost Rome enormous amounts in executions of capable people, political instability, financial recklessness, and diplomatic damage — a reminder of how much a single individual at the top of an autocratic system could damage the whole.