Whether Báetán was king of Tara or not, the real effective power among the northern Ui Neill was Áed mac Ainmuirech.
[8] He is known to have met with Áedán mac Gabráin, king of Dál Riata, in 575 at The Synod or Convention of Drumceat, to agree an alliance, presumably arranged by his cousin Columba.
[11] A challenge to the rule of Áed among the northern Ui Neill was launched by Colcu mac Domnaill of the Cenél nEógain branch.
[14] Another challenge to Áed may have come from the direction of Ulster in the person of Fiachnae mac Báetáin (died 626) of the Dál nAraidi.
[18] Áed came into conflict with Brandub mac Echach, King of Leinster from the Uí Cheinnselaig who was resisting Ui Neill encroachment.
[20] However, at the battle of Dún Bolg (Dunboyke, modern County Wicklow) in 598, Áed was defeated and killed by Brandub.
[22] Áed was followed as king of the Northern Uí Néill by Colmán Rímid, son of Báetán mac Muirchertaig, of the Cenél nEógain.