Rhodri inherited the kingdom of Gwynedd from his father but is renowned for being the first person to unite three of the largest Welsh kingdoms, and defend them against Viking and Saxon raids until his death in 878.
Rhodri was the son of Merfyn ap Gwriad, or Merfyn Frych (d.844), and Nest, the daughter of Cadell ap Brochfael of Powys. He succeeded his father as king of Gwynedd in 844.
The first recorded Viking attack on Wales was around 850, but there were most probably many earlier ones than this. Rhodri also faced a Saxon attack in 853 led by Burgred of Mercia and Aethelwulf of Wessex.
Following the death of his uncle, Cyngen ap Cadell, in 855, Rhodri annexed Powys and he defended Ynys Môn (Anglesey) from a Viking raid shortly afterwards. A year later the ‘Norsemen’ returned and their leader, Gorm, was defeated in battle by Rhodri. By 865, however, the Saxons had managed to drive him from Ynys Môn but he managed to return shortly afterwards to reclaim it.
Rhodri married Angharad ferch Meurig ap Dyfnwallon, king of Seisyllwg - an area which included the regions of Ceredigion and Ystrad Tywi. When Angharad’s brother, Gwgon ap Meurig, died by drowning in 872, Rhodri took control of his lands and this was the first time that three of the main kingdoms of Wales had been united.
Rhodri continued to defend Wales against Viking and Saxon attacks for the remainder of his rule. The Vikings managed to drive him into exile in Southern Ireland in 877, although he returned within a year to reclaim his lands. Rhodri was killed in 878, probably by a Mercian force led by Ceolwulf.
Two of his sons, Anarawd and Cadell, went on to found the houses of Aberffraw (Gwynedd) and Dinefwr (Deheubarth), respectively, but Rhodri is best remembered as the person who managed to unite three Welsh kingdoms and then defend them against foreign invaders. As such, his reign was a turning point in the history of Wales.
Twenty-one Welsh Princes by Roger Turvey
National Library of Wales: Dictionary of Welsh Biography - Rhodri Mawr
Merfyn Frych - father Gwgon ap Meurig - brother-in-law
Anarawd ap Rhodri - son Cadell ap Rhodri - son (see Hywel Dda)
Cyngen ap Cadell - uncle Hywel ap Rhodri Molwynog - great-uncle
Cynan Dindaethwy - great-grandfather
Seisyll ap Clydog - ancestor of Rhodri’s wife, Angharad