Rhys ap Tewdwr Rhys ap Tewdwr ( before 1065 – 1093 ) was a king of Deheubarth in Wales and member of the Dinefwr dynasty , a branch descended from Rhodri the Great . He was born in the area which is now Carmarthenshire and died at the battle of Brecon in April 1093 . Family . Rhys ap Tewdwr , a member of the House of Dinefwr , claimed the throne of Deheubarth following the death of his second cousin Rhys ab Owain , who was beheaded after the battle of Gwdig ( modern day Goodwick ) against Caradog ap Gruffydd in 1078 . He was a grandson of Cadell ab Einion ab Owain ab Hywel Dda , and a great - grandson of Einon ab Owain , thus a descendant of Hywel Dda , king of the Britons . He married Gwladys ferch Rhiwallon daughter of Rhiwallon ap Cynfyn of the Mathrafal dynasty of Powys , by whom he had four sons , Gruffudd , Hywel ap Rhys , Goronwy and Cadwgan , and a daughter Nest ( who married Gerald de Windsor Constable of Pembroke , progenitor s of the FitzGerald and de Barry dynasties of Ireland . These celebrated Hiberno - Norman , or Cambro - Norman , families have been Peers of Ireland since at least the 14th century . The English variant of Tewdwr is Tudor . Henry Tudor , King of England was a matrilineal descendant of Rhys ap Tewdwr . Early rule . In 1081 Caradog ap Gruffydd invaded Deheubarth and drove Rhys to seek sanctuary in the St David ' s Cathedral . Rhys however made an alliance with Gruffydd ap Cynan who was seeking to regain the throne of the Kingdom of Gwynedd , and at the Battle of Mynydd Carn in the same year they defeated and killed Caradog ap Gruffydd and his allies Trahaearn ap Caradog of Gwynedd and Meilyr ap Rhiwallon . Norman homage . The same year William the Conqueror visited Deheubarth , ostensibly on a pilgrimage to St David ' s , but with a major show of power as well , traversing the width of southern Wales , and it seems likely he came to an arrangement with Rhys , whereby Rhys paid him homage and was confirmed in possession of Deheubarth . Rhys paid William £40 a year for his kingdom , ensuring good future relations with William that lasted until the end of his lifetime . Rhys was content with the arrangement as it meant that he only had to deal with the jealousy of his fellow Welsh princes . Internal conflict . In 1088 Cadwgan ap Bleddyn of Powys attacked Deheubarth and forced Rhys to flee to Ireland . However , Rhys returned later the same year with a fleet from Ireland and defeated the men of Powys , in a battle in which two of Cadwgan ' s brothers , Madog and Rhiryd , were killed . In 1091 he faced another challenge in the form of an attempt to put Gruffydd , the son of Maredudd ab Owain , on the throne of Deheubarth . Rhys was able to defeat the rebels in a battle at St . Dogmaels , killing Gruffydd . Death . Rhys was unable to withstand the increasing Norman pressure . The Welsh " Brut s " state that " Rhys ap Tewdwr , king of Deheubarth , was slain by the Frenchmen who were inhabiting Brycheiniog . " The Brut y Tywysogion adds " and with him fell the kingdom of the Britons " . This passage lends evidence to the belief that the conquest of Brycheiniog ( Brecon ) , led by Bernard de Neufmarche , was mostly finished by Eastertide 1093 . The battle of Brecon opened the way to the conquest of Deheubarth . Succession . Upon Rhys ' s death , the Normans seized much of South Wales , and fighting over the spoils with the chieftains of Powys and Gwynedd . Eventually , Rhys ' s oldest son , Gruffydd , was allowed to inherit a small portion of his father ' s kingdom . Rhys ' s daughter Nest was briefly one of the numerous concubines of Henry I , to whom she bore a son , and thereafter the wife of Gerald FitzWalter of Pembroke ; their sons and grandsons , the FitzGerald conquerors of Ireland , were known collectively as the " sons of Nest " . Through his son Gruffydd , Rhys was an ancestor of the Tudor dynasty .