The Uí Chonaing had conquered the Ciannachta tribe of Brega, between the Boyne and the Delvin, in the reign of Cináed mac Írgalaig (died 728).
[1] In 749 Dúngal won the battle of Ard Ciannachta versus this tribe and their chief, Ailill mac Duib dá Crích, was slain.
The Annals of Tigernach make the same statements regarding the fortunes of the battle and Domnall's title but claim that Dúngal was victor.
[2] In 759 Dúngal fought the Battle of Emain Macha against Fiachnae mac Áedo Róin (died 789), King of Ulaid.
He was defeated and slain along with his ally Donn Bó mac Con Brettan, king of Fir Rois.