Battle of Mynydd Carn

Date	1081
Location	north of St David's (However, see note below)
Result	Victory for Gruffudd and Rhys

Belligerents

Gruffudd ap Cynan
Rhys ap Tewdwr

Trahaearn ap Caradog †
Caradog ap Gruffydd †

Casualties and losses

Unknown, said to be light

Unknown, Trahaearn, Caradog and other notables killed

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.

The battle took place about a day's march north of St David's. In the evening Gruffudd and Rhys came up with the forces led by Trahaearn and Caradog ap Gruffydd, who are reported to have had Norman arbalisters in their army. According to his biography, Gruffudd ap Cynan insisted on an immediate attack, overruling Rhys who wished to wait until the following morning. The result was a complete victory for Gruffudd ap Cynan and Rhys ap Tewdwr, with Trahaearn ap Caradog, Caradog ap Gruffydd and Meilir ap Rhiwallon all being killed.

...
Wikipedia