A personage who became known to history because of an obscure reference by the Roman writer Juvenal, made between the years AD 80 and 90, in which Arviragus appears as a British opponent of the Romans.
Geoffrey makes him a king of Britain, son of King Cymbeline and the brother of Guiderius. Guiderius became king of Britain after Cymbeline's death, and broke faith with Rome and went to war with Emperor Claudius.
When Guiderius was killed in Claudius's invasion of Britain in AD 43, Arviragus ascended the throne. He made peace with the empire, and married Claudius's daughter, Genuissa (Genvissa), on the banks of the River Severn where Arviragus and Claudius jointly founded the city of Gloucester. Later Arviragus revolted, braking with Rome again a few years later, but he was quelled by the Roman General Vespasian.
Peace was restored through Genvissa's good offices. Eventually, he quieted down and became a benevolent, just king. When he died, his son Marius succeeded him.
G. Ashe thinks Arviragus may have been a local prince in the Somerset area who maintained his independence after the Claudian conquest. I.H. Elder identifies him with Caratacus, while E. Ratcliffe and J. Whitehead all argue that Arviragus, Caratacus and Arthur were different names for the same persons.
Arthurs, Succession of | The Legend of King Arthur