With the help of Donnchad Ua Cerbaill, king of Airgíalla, Áed was able to become king of Tír Eogain himself, though for much of the time he was forced to share the position with a Meic Lochlainn. Áed secured his hold on kingship partly by submitting to the Connacht high king Ruaidrí Ua Conchobair. As one of the latter's chief vassals, he was involved in the early stages of resistance to the Anglo-Norman invasion of Ireland.