Henry), resulting in a pre-emptive English invasion, in 1245. Dafydd died without heirs the next year, but the war was continued by Gruffydd's sons until 1247, when they decided to make peace with the King - the Treaty of Woodstock. The Treaty gave Henry the Perfeddwlad, which he gave to his own son (Edward), while the rest of Gwynedd was divided between Gruffydd's two adult sons (Llywelyn and Owain). After a decade, the population of the Perfeddwlad felt that their grievances were not being adequately addressed by Edward, and appealed to Llywelyn for assistance. Llywelyn was himself already aggrieved that when Llywelyn's younger brother, Dafydd, had reached adulthood, Henry had promised to re-divide Gwynedd so that Dafydd would also have lands to rule. So it was that in late 1256 Llywelyn invaded the Perfeddwlad, and captured it. Supply-line problems led to a series of defeats for the English, who subsequently had to abandon their campaign to deal with serious conflicts between the King and his Barons. In 1269, the King's weakened authority over the whole kingdom, and Llywelyn's gains in the meantime, lead to the Treaty of Montgomery, by which Henry acknowledged Llywelyn's gain of the Perfeddwlad, and his dominance over the rest of Wales - acknowledging Llywelyn as Prince of Wales. However, when Llywelyn married Eleanor de Montfort (in 1275), the daughter of Henry's greatest enemy, Edward - now king of England - demanded an explanation, in person. Llywelyn refused to attend, insisting he wouldn't be safe, so Edward declared him a rebel, and in 1277 attacked Gwynedd with an enormous army, seeking to depose Llywelyn entirely. Once Edward captured the Perfeddwlad and Angelsey (which provided much of the food supply for Llywelyn's troops), Llywelyn sought a peace agreement, resulting in the Treaty of Aberconwy: the Perfeddwlad was divided between Edward and Llywelyn's brother, Dafydd (who had taken Edward's side in the dispute) Llywelyn was permitted to rule the remainder of Gwynedd, Angelsey being restored to him the title Prince of Wales, however, was reduced simply to a label, no longer conferring any authority - all lesser rulers in Wales were released from any obligation to Llywelyn Edward had kept the coastal Cantrefs of the Perfeddwlad, while Dafydd gained Rhufoniog and Dyffryn Clwyd. Nevertheless, by the end of 1281, the Welsh princes who had supported Edward had become disillusioned, and in early 1282 Dafydd attacked the English castles of