The horse was never made consul. Suetonius, the ancient biographer responsible for most of what we think we know about Caligula, never actually claims the emperor appointed his beloved stallion Incitatus to Rome's highest magistracy. What Suetonius wrote was that Caligula intended to do so—a crucial distinction that has been flattened across two millennia of retelling. The anecdote survives not as evidence of madness, but as a reminder that our primary sources for this emperor's reign were written decades after his death by men who had every reason to make him look unhinged.
The Boy in the Army Camp
Gaius Julius Caesar Augustus Germanicus was born on August 31, AD 12, into the most powerful family in the Roman world. His father, Germanicus, was Augustus's adopted grandson and Rome's most celebrated general—a war hero beloved by the legions and the populace alike. His mother, Agrippina the Elder, was Augustus's own granddaughter, making young Gaius a descendant of the first emperor through both parents.
The nickname that would follow him into infamy came from his childhood in military camps along the Germanic frontier. The soldiers adored the toddler who marched among them wearing a miniature legionary's uniform, complete with the heavy-soled hobnailed military sandal-boots called caligae. They called him "Caligula"—"Little Boot." It was affectionate, even diminutive. He reportedly hated it.
His idyllic childhood ended violently. Emperor Tiberius—his adoptive grandfather and the man responsible for his father's career—likely had Germanicus poisoned in AD 19. The family's position collapsed. Agrippina the Elder was arrested, exiled, and starved herself to death. Two of Caligula's brothers died in prison. The young prince survived only by living in the imperial household on Capri under Tiberius's watchful, paranoid eye, learning to hide his true feelings from the man who had destroyed his family.
Six Months of a Different Emperor
When Tiberius died in March AD 37, the twenty-four-year-old Caligula became emperor to universal celebration. He was the son of the beloved Germanicus, the last male survivor of Augustus's bloodline. The Roman people expected a golden age.
For the first six months of his reign, ancient sources record an emperor who released political prisoners, burned Tiberius's files of secret accusations, recalled exiles, and abolished treason trials. He was generous, popular, and by all accounts, sane.
This early period is often dismissed as Caligula simply playing to the crowd before revealing his "true" nature. But another interpretation deserves consideration: the emperor suffered a severe illness in October AD 37. Several ancient sources mention this crisis. Whether it was meningitis, encephalitis, lead poisoning from the Roman water system, or something else entirely, the illness nearly killed him. Some modern historians have suggested this medical episode changed his personality or cognitive function. Others argue the shift in our sources reflects something else entirely—a young emperor who began asserting autocratic power in ways that offended the senatorial aristocracy.
The Problem With Our Sources
Here lies the overlooked variable in everything we think we know about Caligula: every major ancient account of his reign was written by men of the senatorial class, decades after his assassination, under emperors who had every political reason to portray him as a monster.
Suetonius wrote his Lives of the Caesars around AD 121—eighty years after Caligula's death. Tacitus composed his Annals around the same time. Cassius Dio wrote even later, in the early third century. None of them witnessed the events they describe. All of them belonged to or served the senatorial aristocracy—the very class that had the most contentious relationship with Caligula's rule.
The Julio-Claudian dynasty, which comprised the first five Roman emperors from Augustus through Nero, established a political system that was, in practice, an autocracy dressed in republican clothing. The fiction required emperors to perform deference to senatorial traditions. Caligula, by many accounts, refused to play along. He reportedly mocked senators openly, humiliated prominent aristocrats, and expressed the autocratic reality of his power with contempt for the pretense.
This made him enemies—specifically, the class of enemies who would later write the histories.
What the Record Actually Shows
Separating documented actions from hostile interpretation reveals a more complicated figure. Caligula did expand the empire, annexing Mauretania and preparing for campaigns in Britain and Germania. The actual conquest of Britain in AD 43, which marked the beginning of Roman rule there lasting until AD 410, was launched by his successor Claudius—but Caligula had assembled the invasion force.
He maintained close personal relationships that suggest something other than the arbitrary cruelty of legend. Herod Agrippa, the Jewish prince who had been raised alongside him in Rome, became one of his closest friends. When Caligula became emperor, he installed Agrippa as king of territories in the Levant, eventually making him the last client king of Judea. A man incapable of human connection would not have sustained this decades-long friendship or trusted such important territories to its keeping.
Caligula built extensively, completed the Temple of Augustus that Tiberius had left unfinished, began an ambitious aqueduct system, and expanded the imperial palace. He staged elaborate public spectacles and distributed money to the populace. These were expensive—ruinously so. By the end of his reign, the treasury was depleted, and the emperor had resorted to confiscating estates and extracting money from the wealthy through various legal pretexts. This certainly created enemies. Whether it constitutes madness or merely bad fiscal policy is another question.
The accusations of sexual depravity, incest with his sisters, declaring himself a living god, and random murders are harder to assess. Our hostile sources present these as facts. But Roman political invective routinely included accusations of incest and sexual excess against despised rulers—these were stock charges, applied with equal vigor to emperors ancient writers wished to discredit. When Nero's reputation was being destroyed after his suicide, remarkably similar accusations appeared.
This does not mean Caligula was innocent of all the crimes attributed to him. He did execute people, including several of his relatives. He was assassinated by his own Praetorian Guard in January AD 41, suggesting he had made powerful enemies within the military establishment. His reign ended in violence because he was, by many measures, a bad emperor—impetuous, tactless, financially reckless, and fatally dismissive of the men with swords who surrounded him.
But there is a vast distance between "bad emperor" and "mad emperor." The monster of popular imagination—the lunatic who made a horse a consul, who declared war on Neptune, who committed every imaginable depravity—may tell us more about the agenda of our sources than about the man himself. The senatorial class that recorded his memory had survived his reign by keeping their heads down. Their revenge came in ink, decades later, when they could safely make him an example of what happens when an emperor abandons the polite fictions of shared power.
The overlooked variable in Caligula's story is not a person or an event—it is the simple fact that we are reading his enemies' version of history, written by men who belonged to the class he humiliated, under emperors who benefited from his disgrace. That doesn't make him a good ruler. But it should make us suspicious of every colorful detail that has transformed a short-tempered young autocrat into history's favorite madman.