Caligula was killed by his own guards in AD 41

The emperor Caligula was stabbed to death by officers of his own Praetorian Guard on 24 January AD 41, in a covered passage of the palace on Rome’s Palatine Hill. He was 28 and had ruled, by Suetonius’ exact count, three years, ten months and eight days. The plot was led by the tribune Cassius Chaerea, whom Caligula taunted as effeminate, assigning him watchwords such as “Priapus” and “Venus”. At least two other tribunes, the Guard’s prefect, several senators and a powerful imperial freedman were involved.

The violence did not stop with the emperor. Caligula’s German bodyguards killed several of the assassins and some senators who had nothing to do with it. His wife Caesonia was killed by a centurion, and their infant daughter was dashed against a wall. Even then, Suetonius says, many Romans suspected the news was a trick by Caligula to test their loyalty.

For a brief moment the old order seemed to be returning. The conspirators had not agreed on a successor, and the Senate, “unanimously in favour of re-establishing the republic”, met on the Capitol rather than in the Senate house named after the Julian family. Some senators proposed erasing the memory of the Caesars altogether. The Guard ended the debate by proclaiming Caligula’s uncle Claudius emperor. Eighty-four years after Julius Caesar’s murder, killing the ruler again failed to bring back the Republic.

Much of what people “know” about Caligula comes from sources written by his enemies. Suetonius says only that Caligula planned to make his horse Incitatus consul, not that he did. The historian Garrett Fagan, writing in De Imperatoribus Romanis, notes that the only eyewitness account, by the Jewish envoy Philo, portrays him as arrogant and witty but offers little sign of outright madness. Fagan’s verdict is that the reign exposed what Augustus had disguised: the principate was a raw monarchy, and an emperor could not give up his power without giving up his life.