 One of Murchad Óc's sons, Máel Muire, became lord of Fanad, and another son, Donnchad Mór, became lord of the Tri Tuatha in north west County Donegal, which had been conquered from the Ó Báegills.Máel Muire defeated Niall Ó Domhnaill in the battle of Achadh Móna but later became an ally of Ó Domhnaill, when Niall killed his brother, Conchobhar Ó Domhnaill, King of Tír Chonaill in 1342.Because of his aid, Máel Muire was granted the lands of Moross in the north of Fanad.