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
Frederick I, Holy Roman Emperor Frederick I, Holy Roman Emperor Frederick I (, ; 1122 – 10 June 1190), also known as Frederick Barbarossa (), was the Holy Roman Emperor from 2 January 1155 until his death. He was elected King of Germany at Frankfurt on 4 March 1152 and crowned in Aachen on 9 March 1152. He was crowned King of Italy on 24 April 1155 in Pavia and Roman Emperor by Pope Adrian IV on 18 June 1155 in Rome. Two years later, the term ' ("holy") first appeared in a document in connection with his Empire. He was later formally crowned King