 Later Eoghan was able to help Séan Ó Domhnaill defeat Toirdhealbhach an Fhíona Ó Domhnaill in battle, at Sliabh Malair.Eoghan died as they plundered Glencolumkille "as a result of his violating the monastery there".According to the Book of Ballymote, Eoghan's son, Toirdealbhach Óg was lord of Na Tuatha.