According to this, Cummascach mac Cathail of the Uí Cremthainn, king of the Airgíalla, expelled Niall's confessor Éogan Mainistrech from Armagh, installing his own half-brother, Artrí mac Conchobair, who may have been the son of High King Conchobar mac Donnchada, as abbot of Armagh.
According to this account, Cummascach mac Cathail, king of the Airgíalla from the Uí Cremthainn lineage, removed Niall's confessor Éogan Mainistrech from Armagh and placed his own half-brother, Artrí mac Conchobair, who might have been the son of High King Conchobar mac Donnchada, in charge of the abbey at Armagh.