History of the Roman Empire from this point on, leading his biographers to label him as insane. Most of what history remembers of Caligula comes from Suetonius, in his book "Lives of the Twelve Caesars". According to Suetonius, Caligula once planned to appoint his favourite horse Incitatus to the Roman Senate. He ordered his soldiers to invade Britain to fight the Sea God Neptune, but changed his mind at the last minute and had them pick sea shells on the northern end of France instead. It is believed he carried on incestuous relations with his three sisters: Julia Livilla, Drusilla and Agrippina the Younger. He
Roman emperor misrule led to his murder on 31 December 192, following which a brief period of instability quickly gave way to Septimius Severus, who established the Severan dynasty which, except for an interruption in 217–218 when Macrinus was emperor, held the purple until 235. The accession of Maximinus Thrax marks both the close and the opening of an era. It was one of the last attempts by the increasingly impotent Roman Senate to influence the succession. Yet it was the second time that a man had achieved the purple while owing his advancement purely to his military career; both Vespasian and