Claim: Dungarth was a king of Cornwall who drowned in 875 as a punishment for collaboration with the Normans.
Evidence: Donyarth (Latin: Doniert) or Dungarth (died 875) was the last recorded king of Cornwall. According to the Annales Cambriae, he drowned in 875. His death may have been an accident, but it was recorded in Ireland as a punishment for collaboration with the Vikings, who were harrying the West Saxons and briefly occupied Exeter in 876 before being driven out by Alfred the Great following the victory of Odda, Ealdorman of Devon at the Battle of Cynwit in 878. Vikings were the seafaring Norse people from southern Scandinavia (present-day Denmark, Norway and Sweden) who from the late 8th to late 11th centuries raided, pirated, traded and settled throughout parts of Europe, and explored westward to Iceland, Greenland, and Vinland. The Normans, a people partly descended from Norse Vikings who settled in the territory of Normandy in France in the 10th and 11th centuries