Llywelyn ap Iorwerth, << leh oo EH lihn or loo EHL ihn ahp YAWR wurth >> (1173?-1240), also known as Llywelyn the Great, was a Welsh prince. His name means Llywelyn, son of Iorwerth. Llywelyn ruled the territory of Gwynedd in northwestern Wales. He tried to unify the Welsh under the rule of a single, hereditary prince but did not succeed.
In 1194, Llywelyn became ruler of part of Gwynedd. By 1203, he ruled all of it and had begun to extend his control over other parts of Wales. At that time, most of western and central Wales was divided among local, largely independent Welsh rulers, and most of the east and south was controlled by English nobles.
In 1211, King John of England attacked Llywelyn and forced him to give up part of his lands. Other Welsh leaders then allied with Llywelyn and attacked the English nobles in Wales. Llywelyn also allied with barons in England who rebelled against John. In 1215, the English barons forced John to agree to the settlement now known as Magna Carta (Great Charter). Magna Carta placed the king under English law and limited his power.
Because of Llywelyn’s participation in the rebellion, three clauses in Magna Carta addressed Welsh issues. They promised the return of illegally seized lands and of hostages held by the English. They also recognized the use of traditional Welsh law in areas controlled by Welsh lords.
Through wars and alliances, Llywelyn continued to increase the territory under his direct rule, and many Welsh rulers swore allegiance to him. He eventually brought most of Wales under his control. Llywelyn died in April 1240. His son Dafydd (also spelled David) succeeded him, but Dafydd was unable to hold onto all of his father’s territory and authority.