In 1160, Muirchertach was killed at the battle of Magh Lughad (Maloon, near Cookstown), allegedly struck down "innocently" [Annals of Ulster] by Lochlann Mac Lochlainn, kinsman of the king of Tir Eogain and high king of Ireland Muirchertach Mac Lochlainn [REF].
The aftermath of this killing is unclear, but in 1166 following the blinding of the Ulaid king Eochaid Mac Duinn Sléibe, the Mac Lochlainn had to contend with rebellion from Airgíalla, Breifne, and even southern Tír Eogain [REF].