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 Problem with the Sources
Almost everything we know about Caligula comes from sources written long after his death by authors with strong biases. Suetonius wrote his biography roughly 80 years after Caligula's death. Cassius Dio wrote even later. The Senatorial class — who produced Rome's historians — had been humiliated and terrorised by Caligula, giving them every reason to paint him as a monster. Modern historians treat the most extreme accounts with significant scepticism.
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.
Frequently Asked Questions
Was Caligula really insane?
Modern historians are sceptical of the ancient accounts portraying Caligula as simply mad. Almost all sources were written by members of the Senatorial class he humiliated and terrorised, giving them strong motivation to exaggerate or fabricate stories. The more likely explanation is a combination of political trauma from his early years, the corrupting effect of absolute power, and possibly serious illness that changed his behaviour.
Did Caligula really make his horse a consul?
The horse story — that Caligula made his favourite horse Incitatus a consul — is almost certainly either an exaggeration or a political gesture rather than literal truth. Most historians believe it was Caligula's way of demonstrating his contempt for the Senate, suggesting that even a horse could do their job as well as they could. Whether he actually intended to carry it out is unknown.
How did Caligula die?
Caligula was assassinated on 24 January 41 AD by officers of the Praetorian Guard, led by Cassius Chaerea, whom Caligula had repeatedly humiliated. He was stabbed 30 times in a palace corridor. His wife Caesonia and infant daughter were also killed. He was 28 years old and had ruled for less than four years.
What did Caligula do that was so bad?
Ancient sources describe Caligula executing people without trial, declaring himself a living god, committing incest with his sisters, forcing senators' wives into prostitution and demanding his statue be placed in the Jerusalem Temple. Modern historians treat the most extreme accounts with scepticism but the general picture of a cruel and erratic ruler is probably accurate.
Who ruled Rome after Caligula?
After Caligula's assassination the Praetorian Guard discovered his uncle Claudius hiding in the palace — reportedly in terror — and acclaimed him emperor. The Senate briefly discussed restoring the Republic but ultimately accepted Claudius. He proved to be a surprisingly capable ruler, expanding the empire and implementing administrative reforms.
A Note From The Editor
What Caligula's story really demonstrates isn't madness — it's what happens when a system places absolute power in the hands of a single person with no meaningful checks or consequences. Caligula didn't become dangerous because he was uniquely evil. He became dangerous because the Roman system had been structured, under Augustus and Tiberius, to make the emperor essentially unaccountable. Caligula was the logical endpoint of that architecture. The madness was in the system, not just the man.
This is a topic where the conventional explanation misses much of what actually happened.
How much of what we know about Caligula comes from reliable sources — and how much was political character assassination by his successors?