What Led to the Assassination of Emperor Caligula?

For four years, Caligula ruled Rome as an absolute monarch and mocked the Senate—until the senators and the Praetorian Guard assassinated the young but arrogant emperor.

Oct 31, 2023By Vedran Bileta, MA in Late Antique, Byzantine, and Early Modern History, BA in History

what led to the assassination of caligula


Emperor Caligula’s brief four-year reign was marked by a bitter struggle with the Senate of Rome, which soon became an open conflict. Caligula wanted to rule as an absolutist monarch, emulating the Hellenistic god-kings he greatly admired. The Senate, however, wanted to regain and increase its power and influence, curtailed by the establishment of the Roman Empire. Caligula had the army on his side and enjoyed the popular support. However, his autocratic style of rule, paired with his erratic and arrogant behavior, gradually undermined the emperor’s position. When Caligula insulted a Praetorian officer, the senators jumped at the rare opportunity and plotted a conspiracy, which led to Caligula’s assassination in 41 CE.


Emperor Caligula Made Enemies Quickly

caligula cuirass bust roman emperor
Cuirass bust of emperor Caligula, 37-41 CE


Born Gaius Julius Caesar, Emperor Caligula ascended to the throne in 37 CE following the death of his uncle, emperor Tiberius. Caligula was warmly welcomed by both the Senate and the people of Rome. Young and charismatic, emperor Caligula reverted many of Tiberius’ unpopular policies, abolished high taxes, and offered amnesties for political prisoners. However, following his short but near-mortal illness, Caligula became increasingly more paranoid and hostile to the Senate. The emperor considered the senators as the main obstacle to his absolutist rule and blamed them for conspiracies, both real and imagined. No wonder that in only four years of his reign, Caligula made numerous enemies.


The Roman Senate Was Caligula’s Main Rival

roman senate house curia
Cicero Denounces Catiline by Cesare Maccari, 1888, in the Maccari Hall of Palazzo Madama, Rome


Caligula ruled in the early days of the Roman Empire. However, unlike his predecessors – emperors Augustus and Tiberius – who avoided monarchical trappings, Caligula was determined to rule as an absolutist monarch. This led to a collision with the Senate of Rome, who wanted to regain the power and influence it held during the period of the Roman Republic. In 39 CE, Caligula delivered a hostile speech before the Senate, accusing them of treason and disloyalty to his family. The emperor also transferred the last senatorial proconsular legion in Africa under his personal command, further worsening his relationship with the Senate. 


Caligula Enjoyed Mocking the Senators

corona caligula incitatus
Caligula Appointing His Horse Incitatus to the Consulship, unknown author, 1616–1669. Source: The Art Institute of Chicago

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If we are to believe historian Suetonius, Caligula enjoyed humiliating the senators by making them run behind his litter or forcing them to fight for his amusement. He also conceived a series of elaborate pranks. The story of the pontoon bridge over the Bay of Naples, and the infamous tale of Incitatus, Caligula’s favorite racehorse whom he planned to make a consul, are well-known examples of the boy-emperor’s madness. However, such scandalous stories should be seen not as a display of Caligula’s eccentricity but as a calculated move to undermine the Senate’s authority. Super-wealthy and well-educated, the senators could do little to stop Caligula and his soldiers’ drunken debauchery right next to their lavish villas. Caligula clearly pointed to them that they were useless, as even the horse could do their job better. 


Caligula Underestimated the Senate

emperor caligula horse statue
Statue of a youth on horseback (probably representing emperor Caligula), early 1st century CE. Source: The British Museum, London


What started as a harmless but humiliating prank soon turned into a bloody conflict. Senators tried and failed to remove the emperor in one of the numerous assassination plots. Caligula responded in kind, persecuting and imprisoning many of his opponents, both real and imagined. Over thirty senators lost their lives in the bloody purges. Things got even worse when Caligula, perhaps in an attempt to bolster his security, decided to move the capital to Alexandria, where he would rule as a living god, emulating the Ptolemaic god-kings. Caligula’s declaration of godhood broke with all traditional norms, alarming the senators. Even more concerning was the decision to move the center of power to Egypt, where a senator could travel only with the emperor’s permission. 


Caligula Was Assassinated in a Palace Plot

praetorian guard
Relief depicting the Praetorian Guard (originally part of the Arch of Claudius), 51-52 CE. Source: Louvre-Lens, Lens


In his brief four-year reign, Emperor Caligula managed to alienate most of his allies. Yet, the Senate was powerless to strike, as the emperor enjoyed the protection of the Praetorian Guard. When Caligula, who lacked diplomatic skills, insulted a Praetorian officer named Cassius Chaerea, the senators got the much-needed opportunity. On January 21, 41 CE, following Caligula’s favorite pastime, the games, Cassius and other conspirators ambushed the emperor who deviated from his usual guarded route. Chaerea approached Caligula and struck a first blow. The rest of the conspirators followed, stabbing the emperor thirty times and continuing to attack after he was dead. Caligula’s wife and daughter were also killed to eliminate a potential successor. It seemed that the Roman Empire reached its sudden end.  


The Senators Made Emperor Caligula a Villain

alma tadema death emperor caligula
A Roman Emperor: 41 AD, by Sir Lawrence Alma-Tadema, 1871. Source: the Walters Art Museum, Baltimore


The senators’ celebration, however, was premature as the Praetorians elected a new emperor, Caligula’s uncle Claudius, whom they found hiding behind the curtains. Both the army and the Praetorian Guard stood behind the new emperor. There was also the matter of the Caligula’s German bodyguard, who went on a murder spree, killing those involved and those suspected of plotting. However, the senators did their best to vilify Caligula’s name for posterity. Senators like Suetonius were the ones who wrote history and used their power to tarnish the reputation of the ill-fated rulers to justify their removal and legitimize later imperial dynasties. Thus, Caligula, an arrogant boy and average autocrat,  became a madman, a tyrant and an epic villain.

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By Vedran BiletaMA in Late Antique, Byzantine, and Early Modern History, BA in HistoryVedran is a doctoral researcher, based in Budapest. His main interest is Ancient History, in particular the Late Roman period. When not spending time with the military elites of the Late Roman West, he is sharing his passion for history with those willing to listen. In his free time, Vedran is wargaming and discussing Star Trek.