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 Emperor Theodosius I's sons Arcadius and Honorius succeeded as co-emperors. Eighty-five years later, following Germanic migrations which had reduced the empire's effective control across Brittania, Gaul and Hispania and a series of military coup d'état which drove Emperor Nepos out of Italy, the idea of dividing the position of emperor was formally abolished by Emperor Zeno (480). The Roman Empire survived in the east until 1453, but the marginalization of the former heartland of Italy to the empire had a profound cultural impact on the empire and the position of emperor. In 620, the official language was changed from Latin