When Tiberius died on 16 March 37 AD, his estate and the titles of the principate were left to Caligula and Tiberius’s own grandson, Gemellus, who were to serve as joint heirs. Although Tiberius was 77 and on his death bed, some ancient historians still conjecture that he was murdered. Tacitus writes that the Praetorian Prefect, Macro, smothered Tiberius with a pillow to hasten Caligula’s accession, much to the joy of the Roman people. Seneca the Elder and Philo, who both wrote during Tiberius’s reign, record Tiberius as dying a natural death. Backed by Macro, Caligula had Tiberius’s will nullified with regard to Gemellus on grounds of insanity, but otherwise carried out Tiberius’s wishes.
Caligula accepted the powers of the principate as conferred by the senate and entered Rome on 28 March amid a crowd that hailed him as “our baby” and “our star”, among other nicknames. As Pharaoh of Egypt, he adopted the royal titulary Kyseres Kernykes, Autokrator Heqaheqau Meryptahaset, Kanakht Iakhwsetutreiah, (“Caesar Germanicus, Emperor and ruler of rulers, beloved by Ptah and Isis, the strong bull, the light of the sun and the moon’s rays”). Caligula is described as the first emperor who was admired by everyone in “all the world, from the rising to the setting sun.” Caligula was loved by many for being the beloved son of the popular Germanicus, and because he was not Tiberius.
Caligula’s first acts were said to be generous in spirit, though many were political in nature. To gain support, he granted bonuses to the military, including the Praetorian Guard, city troops and the army outside Italy. He destroyed Tiberius’s treason papers, declared that treason trials were a thing of the past, and recalled those who had been sent into exile. He helped those who had been harmed by the imperial tax system, banished certain sexual deviants, and put on lavish spectacles for the public, including gladiatorial games.
In October 37 AD, Caligula fell seriously ill, or perhaps was poisoned. He soon recovered from his illness, but many believed that the illness turned the young emperor toward the diabolical: he started to kill off or exile those who were close to him or whom he saw as a serious threat. Perhaps his illness reminded him of his mortality and of the desire of others to advance into his place. He had his cousin and adopted son Tiberius Gemellus executed – an act that outraged Caligula’s and Gemellus’s mutual grandmother Antonia Minor. She is said to have committed suicide, although Suetonius hints that Caligula actually poisoned her. He had his father-in-law Marcus Junius Silanus and his brother-in-law Marcus Lepidus executed as well. His uncle Claudius was spared only because Caligula preferred to keep him as a laughing stock. His favourite sister Julia Drusilla died in 38 AD of a fever: his other two sisters, Livilla and Agrippina the Younger, were exiled. He hated being the grandson of Agrippa and slandered Augustus by repeating a falsehood that his mother was actually conceived as the result of an incestuous relationship between Augustus and his daughter Julia the Elder.
Philo of Alexandria and Seneca the Younger describe Caligula as an insane emperor who was self-absorbed, angry, killed on a whim, and indulged in too much spending and sex. He is accused of sleeping with other men’s wives and bragging about it, killing for mere amusement, deliberately wasting money on his bridge, causing starvation, and wanting a statue of himself erected in the Temple of Jerusalem for his worship. Once, at some games at which he was presiding, he ordered his guards to throw an entire section of the audience into the arena during the intermission to be eaten by the wild beasts because there were no prisoners to be used and he was bored.
In early AD 41, Caligula was assassinated as a result of a conspiracy by officers of the Praetorian Guard, senators, and courtiers. The conspirators’ attempt to use the opportunity to restore the Roman Republic was thwarted, however. On the day of the assassination of Caligula, the Praetorians declared Caligula’s uncle, Claudius, the next Roman emperor. Although the Julio-Claudian dynasty continued to rule the empire until the fall of Nero in AD 68, Caligula’s death marked the official end of the Julii Caesares in the male line.