In 1276, Edward I of England began a campaign against Gwynedd after Llywelyn, prince of Wales, refused to pay homage. Edward’s army marched towards Gwynedd in 1277 and quickly subdued its Welsh vassals as many were unhappy under Llywellyn’s rule. Llywelyn was forced to sign away lands to become English vassals under the treaty of Aberconwy and Edward began constructing castles around the territory of Gwynedd. After a period of peace, war flared up again in 1282 when Llywelyn’s exiled brother Dafydd gathered support from the former Welsh vassals and attacked the English border, with Llywelyn’s forces joining soon after. After killing Llywelyn and Dafydd and subduing the Welsh rebellion with a three-pronged attack, Edward installed English nobles alongside loyal Welsh rulers to consolidate his control of Welsh territory. He also began a programme of English settlement around a series of new, formidably constructed castles which could receive supplies from the sea.
— OR —