Realising the fight was hopeless, Llywelyn surrendered unconditionally to the Earl of Hereford at Ystradfellte on 18 March 1316, but pleaded that only he should be punished and his followers should be spared.
In 1318 Llywelyn became the prisoner of the ruthless Hugh the younger Despenser, one of King Edward's favourites at court who had become Lord of Glamorgan in November 1317 and thus the largest land owner in South Wales, and was a great rival of Mortimer.