Battle of Clontarf, 1014. Probably the largest battle in Gaelic Irish history prior to the Norman Invasion.

The forces of the newly united Kingdom of Ireland under High King Brian Boru face off against an invading army of Norsemen from overseas, who are hoping to kickstart another chapter in Ireland's Viking Age. The Norsemen are defeated, but the battle is so vast and so destructive that both the High King and his heirs are also killed.