Gwenddoleu ap Ceidio died at the Battle of Arfderydd, a battle in 573 recounted in Old Welsh sources.
Little is known of his reign, but it ended when, as described in the Annales Cambriae, the sons of Eliffer, Peredur and Gwrgi, the joint kings of Efrog, killed him at the Battle of Arfderydd in 573. The opposing armies are variously given in a number of Old Welsh sources, perhaps suggesting a number of allied armies were involved. 
