Gwenwynwyn seized Arwystli in 1197 when he was aligned with England. Following the marriage of Llywelyn the Great and Joan of England in 1208, warfare broke out once more between Gwenwynwyn and Llywelyn. In 1212 Gwenwynwyn's ancient royal seat at Mathrafal was destroyed and he was evicted from his territories. He changed allegiances again and was restored to his realm in 1215 making a new capital at Welshpool. In 1216 he was defeated in battle with the forces of Llywelyn and fled to England, where he died shortly afterwards. He was succeeded by his son.
Gruffydd ap Gwenwynwyn was forced to submit to Llywelyn Fawr in 1216. Like his father he repeatedly switched allegiances and was invested with the lordships of Arwystli, Cyfeiliog, Mawddwy, Caereinion, Y Tair Swydd and Upper Mochnant by Henry III of England in 1241.
Gruffydd ap Gwenwynwyn married Hawise daughter of John Le Strange of Salop in 1241. He transferred his allegiance back to Llywelyn ap Gruffydd in 1263 before returning to England's protection again after 1276 following a failed plot to murder Prince Llywelyn in collusion with his rival's own brother, Dafydd ap Gruffydd. His forces commanded by his son Owen mobilised during the Welsh War of 1282–1283 with those of John Le Strange and Hugh le Despenser and it was their soldiers who ambushed and killed the last native Prince of Wales near Builth on that fateful day in 1282.
Owain ap Gruffydd ap Gwenwynwyn alias de la Pole (ie. of Welshpool); allegedly surrendered the principality of Powys to Edward I at the Parliament of Shrewsbury in 1283 (his rival in Powys Fadog had already been deposed for fighting on the wrong side). In return for surrendering the principality he received it again from the king as a free Baron of England "sub nomine et tenura liberi Baronagii Angliæ, resignando Domino Regi heredibus suis et Coronæ Angliæ nomen et circulum principatus." The date should be accepted with reserve because Owen did not succeed his father in possession till 1286 - it is possible that Owen was acting on his father's behalf who was by now an old man. It is from about this time that the former princely family began using the Normanized surname de la Pole in favour of Welsh patronymics. The name derives from Pool (now called Welshpool), his principal town.