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
Matthias, Holy Roman Emperor Holy Roman Emperor, as a result of Rudolf's illness. Allying himself with the estates of Hungary, Austria, and Moravia, Matthias forced his brother to yield rule of these lands to him in 1608; Rudolf later ceded Bohemia in 1611. Matthias's army then held Rudolf prisoner in his castle in Prague, until 1611, when Rudolf was forced to cede the crown of Bohemia to his brother. After Matthias's accession as Holy Roman Emperor, his policy was dominated by Klesl, who hoped to bring about a compromise between Catholic and Protestant states within the Holy Roman Empire in order to strengthen it.