Llywelyn ab Iorwerth (1173–1240), prince of Gwynedd (1195–1240), known as ‘the Great’. The son of Iorwerth ‘Flatnose’ and Margaret, princess of Powys, Llywelyn spent most of his life restoring and enhancing the hegemony of his grandfather Owain Gwynedd. A striking youth and a successful warrior at an early age, he acquired (from 1194) lands at the expense of his kinsmen, enabling him to master Gwynedd by 1203. Good relations with King John brought recognition and his marriage to John's natural daughter Joan. But his aggression towards Powys made John retaliate (1210–11) and Llywelyn then allied with the French. He aided the rebel barons and exploited the civil war in England to extend his power to modern Carmarthenshire and Cardiganshire and east towards Montgomery, making himself lord of Powys by 1216. Henry III's regime recognized all this (1218), and despite hostilities with marcher lords like the Marshalls, he sustained his position by marriage alliances with other lords like the Braoses. He planned to perpetuate his principality by securing recognition from king and pope (1220–2) of his son Dafydd as his sole heir, even though this breached Welsh custom and alienated his elder son, the bastard Gruffydd. He took the evocative title of prince of Aberffraw and lord of Snowdon (1230), which seemed to imply suzerainty over other Welsh lords, and he compared himself to the king of Scots; but Llywelyn did not deny his own homage to Henry III. Llywelyn probably suffered a stroke in 1237 and after his death (11 April 1240) he was buried at Aberconwy abbey which he had patronized, leaving Dafydd to assert the position his father had bequeathed to him.

Ralph Alan Griffiths

Llywelyn ap Iorwerth (1173–1240) ( Llywelyn the Great) Prince of Gwynedd, Wales. He overcame dynastic rivals and captured Mold from the English in 1199. He established his suzerainty in Gwynedd, subsequently gaining control of Powys also. He allied himself with the English barons against John and was recognized as suzerain by all the Welsh princes.