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 his "auctoritas" and pious respect for tradition. Some later historians such as Tacitus would say that even at Augustus' death, the true restoration of the Republic might have been possible. Instead, Augustus actively prepared his adopted son Tiberius to be his successor and pleaded his case to the Senate for inheritance on merit. The Senate disputed the issue but eventually confirmed Tiberius as "princeps". Once in power, Tiberius took considerable pains to observe the forms and day-to-day substance of republican government. Rome had no single constitutional office, title or rank exactly equivalent to the English title "Roman emperor". Romans of