When Merfyn died, or was killed, in 844, his son Rhodri was perhaps 24/26 years old. It is possible that Merfyn's brother Cadrod acted as interim king until Rhodri attained "full age"... 1
[The Gwentian Chronicle records that "Rhodri the Great, son of Mervyn the Freckled began to reign over the Welsh" in 843.]
King of Gwynedd. [The Gwentian Chronicle records that "Rhodri the Great opposed [Berthwrd king of Mercia]…with the assistance of Meuryg son of Hywel king of Glamorgan" in 843, adding that Meuryg was killed in the battle and was succeeded by "Ithel son of Hywel" who was killed by "the men of Brecknockshire" on his way to assist Rhodri. He succeeded his maternal uncle Cyngen ap Cadell as King of Powys in 855. He succeeded in 872 as King of Seisyllwg. The Annals of Ulster record that "Rhodri son of Merfyn king of the Britons came in flight from the dark foreigners to Ireland" in 877. The Annales Cambriæ record that "Rotri et filius eius Guriat…jugulatur" in 877 by the Saxons.
The Chronicle of the Princes of Wales records that "Rhodri and his brother Gwriad were killed by the Saxons" in 878. The Annals of Ulster record that "Rhodri son of Merfyn king of the Britons was killed by the Saxons" in 878. The Gwentian Chronicle records "the action…in Mona in which Rhodri and his brother Gwriad, and Gweirydd son of Owain of Glamorgan were killed by the Saxons" in 873 (dated in other sources to 878). 2
RHODRI MAWR (‘ the Great ’) (d. 877 ), king of Gwynedd, Powys, and Deheubarth; son of Merfyn Frych by Nest, daughter of Cadell ap Brochwel of Powys . He succeeded his father as king of Gwynedd in 844. In 855 , on the death of his uncle, Cyngen, he became king of Powys, and in 872, when Gwgon, king Seisyllwg (Ceredigion and Ystrad Tywi) and brother to his wife, Angharad, died, the southern realm came under his rule. There was thus created for the first time a loose union of at least three major Welsh provinces, and though dissolved at Rhodri 's death, this temporary association gave birth to an aspiration which coloured the outlook of successive generations of Rhodri 's descendants as rulers of Deheubarth or Gwynedd down to the loss of Welsh independence. In his life-time Wales was gravely menaced by the Danes, and evidence exists pointing to bold and vigorous leadership during this crisis. It would appear that he died in battle against the Saxons , leaving six sons of whom two became founders of medieval dynasties, Anarawd of the house of Aberffraw, and Cadell, father of Hywel Dda, of the house of Dinefwr. 3