Battle of Mynydd Carn
1081 CE.
Shown on the map at 51.764°, -4.760°.
The Battle of Mynydd Carn took place in 1081, as part of a dynastic struggle for control of the Welsh kingdoms of Gwynedd and Deheubarth. The result of the battle had a radical effect on the history of Wales. The battle is recorded in the near-contemporary biography of one of the participants, The History of Gruffydd ap Cynan. Gruffudd ap Cynan was a descendant of the traditional ruling house of Gwynedd, and had previously made an attempt to claim the kingdom in 1075, but had been defeated by Trahaearn ap Caradog and forced to take refuge in Ireland. In 1081, Gruffudd launched an invasion from Waterford in Ireland, having gathered a force of Danes and Irishmen to support his claim. He landed not in Gwynedd but further south near St David's (in what would become the Paladin of Pembrokeshire). At the church of St David's he met with Rhys ap Tewdwr, king of Deheubarth who had shortly before been driven from power by Caradog ap Gruffydd of Glamorgan and Gwent helped by Meilir ap Rhiwallon of Powys and Gruffudd's old nemesis Trahaearn ap Caradog of Gwynedd. Gruffudd and Rhys made a pact and set forth to give battle.
Text from the Wikipedia article Battle of Mynydd Carn, licensed CC BY-SA 4.0.