Criccieth Castle a distant relation of Llywelyn ap Gruffudd, began an uprising against English rule that spread quickly through Wales. Several English-held towns were razed and Criccieth (along with Harlech Castle and Aberystwyth Castle) were besieged that winter. Its residents survived until spring when the castle was resupplied. In the 14th century the castle had a notable Welsh constable called Hywel ap Gruffydd, known as Howell the Axe, who fought for Edward III at the Battle of Poitiers in 1356. The castle was used as a prison until 1404 when Welsh forces captured the castle during the rebellion of Owain Glyndŵr. The
Dyfnwal ab Owain by another son of Dyfnwal named Owain, who is recorded to have died in 1015. The later Owain Foel, King of Strathclyde, who is attested in 1018, may well be a grandson of Dyfnwal. Dyfnwal is likely the eponym of Dunmail Raise in England, and possibly Cardonald, Dundonald/Dundonald Castle in Scotland. For hundreds of years until the late ninth century, the power centre of the Kingdom of Al Clud was the fortress of Al Clud ("Rock of the Clyde"). In 870, this British stronghold was seized by Irish-based Scandinavians, after which the centre of the realm seems to have relocated