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 (Dominate) Roman Emperor (Dominate) The accession on November 20, 284, of Diocletian, the lower-class, Greek-speaking Dalmatian commander of Carus's and Numerian's household cavalry, marked a major departure from traditional Roman constitutional theory regarding the Emperor, who was nominally first among equals during the Principate. Whereas before Emperors had worn only a purple toga and were greeted with deference, Diocletian wore jewelled robes and shoes, and required those who greeted him to kneel and kiss the hem of his robe. In many ways, Diocletian was the first monarchical Emperor, and this is symbolised by the fact that the word "dominus" ("Lord") rapidly