 In 853, the Vikings raided Anglesey, but in 856, Rhodri Mawr defeated and killed their leader, Gorm.The Britons of Wales later made their peace with the Vikings and Anarawd ap Rhodri allied with the Norsemen occupying Northumbria to conquer the north.This alliance later broke down and Anarawd came to an agreement with Alfred, king of Wessex, with whom he fought against the west Welsh.