Cadeyrn was nominally a King of Powys, though how much independence he would have had from his father Vortigern's high-kingdom is unclear. The area was certainly the adopted homeland of the Vorteneu family and therefore it was given to Cadeyrn as Vortigern's second son. Cadeyrn was a warrior king (his name actually means 'Battle-Prince') who led the British troops at the Battle of Rithergabail (Aylesford, Kent) in AD 447, after his brother Vortimer's revolt against their father and his invading Saxon henchmen. He was killed on the battlefield and buried under nearby Kit's Coyty House, a megalithic dolmen. Cateyrn was succeeded on the throne of Powys by his son, Cadell Ddyrnllug. He may have had a second son named Rhuddfedel Frych (the Freckled).