Early lifeCaligula was the son of Germanicus, a prominent general of the Roman Empire who was adopted by Emperor Tiberius. Caligula's name is a nickname coming from the Latin diminutive meaning "little soldier's boot", a name given to him by Roman soldiers while he accompanied his father on campaign. In 19 his father died at Antioch and his mother Agrippina the Elder became entangled in a feud with Tiberius, who wiped out all of the family members except for Caligula. He then became the new heir to his great uncle Tiberius, and he enjoyed a frivolous lifestyle, having an incestuous relationship with his sister Julia Drusilla in addition to having relationships with several Roman women. Caligula was said to have had a "gift for logic" by the jurist Marcus Cocceius Nerva, exemplified when Nerva confronted him about the executions of five of his colleagues in the Roman Senate and the suicides of four more; Nerva claimed that they were good men, but Caligula struck back by telling him that, if they were good men, the emperor would not have had them executed.
Journey to CapriIn 33 AD, Praetorian Guard prefect Naevius Sutorius Macro asked Caligula to meet Emperor Tiberius in Capri, as the dying Tiberius wanted to see him one last time as he slowly died - he had hidden himself away for ten years. Caligula reached Capri with Macro, although he did not like going to visit Tiberius; he greeted the jurist Marcus Cocceius Nerva before visiting his emperor, who had been hidden away for ten years. Tiberius, who was sick with syphillis and deranged, had outbursts while talking with Caligula at his pool, which was filled with (and surrounded by) naked male and female servants. Tiberius had Caligula dance for him, but he abruptly had Caligula stop. Caligula was later hugged by Tiberius, and Caligula pushed his dim-witted uncle Claudius into the pool for laughing at his dance earlier.
Life at Tiberius' courtTiberius took him through his palace and showed him the male "satyrs" and female "nymphs" that held sex shows for him, with some of the people involved being disfigured. Caligula was angered by the mad Tiberius, who threatened to kill him to trick "fate", which said that Caligula would be killed after Tiberius' death. Tiberius even tried to poison him with wine, but Caligula insisted that his stepbrother Tiberius Gemellus be given the cup; Tiberius instead gave it to an African servant girl, who died upon drinking it. As Tiberius left to go upstairs with Gemellus, he said that Caligula would be killed, and Caligula feared for his life. As he fondled Macro's wife Ennia Thrasylla, he heard Tiberius order Caligula's arrest, and Caligula rushed to confront Tiberius, who was watching Nerva die after he slit his wrists. Caligula asked the dying Nerva if he could see the goddess Isis as he died; when he said that all he felt was sleep, Caligula called him a liar and shoved the nearly-dead Nerva under the water, killing him.
Murdering TiberiusCaligula decided to collaborate with Macro to assassinate Tiberius, who was half-paralyzed after the death of Nerva. The Greek physician Charicles told Caligula that he had a year left to live if he was lucky, and Caligula decided to act immediately. He sat at Tiberius' deathbed and, believing that his grandfather had died, took his ring for himself. However, Tiberius woke up and demanded that Caligula give him his ring back, but Caligula refused. Tiberius told him that he would not dare to kill him, as Caligula raised a mirror to strike him. However, Macro took the mirror and put it down, and he suffocated Tiberius to death with a black veil. Caligula was proclaimed emperor at Tiberius' funeral, and the attendees said "to the Tiber with Tiberius!" when he mentioned his grandfather's name in fake sorrow (he had Drusilla give him an onion to stiff to provoke tears), so Caligula decided to gain their support by issuing a general amnesty. He announced that his dim-witted relative Claudius would be made his co-consul, while he adopted Gemellus as his son and heir. Caligula also mandated that the Roman Senate should recognize Drusilla as his co-ruler, much to the Senate's dismay. However, as they held hands and rose them, the people shouted "Hail Drusilla" and "Hail Caesar".
Early reignCaligula's first act was to have Macro arrested after Gemillus identified Macro as the man who killed Tiberius. Macro was silent about his fate, as he swore to Caligula that he would be loyal to him. Caligula appointed Cassius Chaerea as the new Praetorian Guard prefect, and he gave Roman troops 10 more gold coins to gain their loyalty. Caligula had Macro sentenced to death by the senate, and he banished Ennia to Gaul, although she pleaded for mercy for both herself and her husband. Caligula then had the issue of finding a wife; his sister refused to marry him, and she told him that priestesses of Isis were having a gathering, so he could find one there. He wanted to marry Livia, a beautiful virgin, but she was already engaged with Proculus, one of Caligula's officers. Suddenly, a priestess named Milonia Caesonia caught his eye, and he decided to marry her, although she was a promiscuous and extravagant woman with a terrible reputation. Caligula descended into madness, having Macro executed at a public event. He proceeded to have his jealous revenge on Proculus by raping him and his wife at their wedding, and he disappointed his sister; he would later disembowel Proculus and send his severed testicles to Livia. Later, he decided to kill Gemellus for no apparent reason, claiming that Gemellus took a remedy because he believed that Caligula was trying to poison him; Caligula believed that this was tantamount to a false accusation, and therefore treason. He slapped his sister after she called him an amateur, causing her to run away.
Caligula fell ill from fever at the same time as his wife's pregnancy with a daughter, and he would recover; however, Julia Drusilla collapsed from fever as his daughter Drusilla the Younger was born in a public ceremony. When Drusilla died of fever despite Caligula praying to Isis, Caligula destroyed an Isis statue and went on a rampage. Dressed as a beggar, he wandered the streets, with many thinking that he went to Egypt, Greece, Carthage, or Persia, and he was thrown in jail for causing a disturbance at a show mocking Caligula's incestuous relationship with his late sister. He spent a single night in jail, where he met a mute barbarian that became a member of his retinue.
Descent into madnessAfter leaving the city jail, Caligula held a meeting with the Roman Senate, proclaiming himself a god and declaring that the month-long mourning period for Drusilla's death was over. He began making sheep noises with the senators as a blue blanket fell on top of all of them, and guards whipped several people; Caligula's assistant Longinus said that he was mad. Longinus was also told by Caligula of a new idea of his: an imperial brothel to balance the state budget, in which the wealthy senators' wives would become prostitutes. He also alienated Chaerea when he told him to stage an invasion of Britannia in lands that had already been conquered, telling him to destroy the "papyrus" along the shore. At a party in which Caligula presented 100,000 papyrus leaves from "conquered Britain", Longinus made it known to Caesonia that he hated her husband, and Caesonia told this to Caligula; he told her that he did not mind if they hated him, as long as they feared him. At that party, he randomly shouted "I hate them!", and he told the people that he would confiscate the states of "those who have failed Rome": Senators Galba, Aponius, Marcellus, Antonius, Cassius, Chaerea, Rufus, Marcus, Lepidus, Sixtus, and Octavius. Caligula also entertained the idea of permanently moving to Alexandria in Egypt, which would mean that the Senate and Praetorian Guard would be useless in Rome as Caligula's tyranny continued in Egypt. Longinus and Chaerea agreed that they had to assassinate Caligula, as he was humiliating the empire.
Caligula and some Roman actors practiced for an Egyptian play about Isis and Osiris on the day of 24 January 41 AD, with his wife Caesonia playing one of the roles. After practice, they left the stadium, and Caligula led the way up some stairs. Chaerea halted him and asked him for the password; when Caligula said "scrotum" in jest, Chaerea's praetorian guard and a member of Hidden Ones Leonius slashed him with his dagger, wounding him. His men proceeded to kill Caesonia, and a wounded Caligula stood. He shouted "I live!" as Chaerea impale him with his sword, and a shocked Claudius - who was in attendance - had the imperial robe draped over him and was proclaimed emperor. Caligula, his wife, his daughter, and the severed head of his barbarian friend were left on the staircase in a bloody mess, and Claudius was proclaimed emperor by the Praetorians after he was found hiding behind some curtains.