A battle remembered in several Welsh narratives as causing the madness of Myrddin (or Merlin). As a result he fled to the forests of Caledonia [W Celyddon, Scotland] where he lived in trees with wild beasts for half a century; in his frenzied condition he acquired the gift of prophecy. Arfderydd is mentioned in several Welsh narratives and documents; the Annals give its date as 573 or 575. Myrddin fought on the side of Gwenddolau, who was slain by the sons of Eliffer, Gwrgi, and Peredur; Rhydderch of Strathclyde was the victor in battle. The site of the battle is identified with the modern hamlet of Arthuret (derived from Arfderydd) in Cumberlandshire, on the River Esk, 8 miles N of Carlisle.