Gwynedd, kingdom of

Medieval Welsh kingdom comprising north Wales and Anglesey. It was the most powerful kingdom in Wales during the 10th and 11th centuries: its king Gruffydd ap Llewellyn dominated Wales in the mid-11th century and nearly succeeded in uniting the Welsh. When the Normans invaded England, Gwynedd led Welsh resistance against Norman efforts to extend their writ over the border, with mixed success. Llewellyn ap Gruffydd styled himself Prince of Wales in 1258, and the English king Henry III was forced to acknowledge him as such in 1267. Edward I rightly recognized Gwynedd as the key to subduing the Welsh and he launched a major offensive against Llewellyn in 1277, ultimately destroying the kingdom. Gwynedd was broken up and the lands of the ruling dynasty passed to the English Prince of Wales.