The Síl nDlúthaig also had a feud with the main Clann Cholmáin line of Uisnech in Mide.
Flann's father Áed had killed Diarmait Dian mac Airmetaig Cáech, the King of Uisnech in 689.
[2] In 711 the high king Fergal mac Máele Dúin (died 722) of the Cenél nEógain defeated and slew Flann's brother Cú Raí mac Áedo at the Battle of Sliab Fúait (in the Fews, Co.Armagh) along with the king of Uí Méith.
[3] In 712 the feud among the Síl nÁedo Sláine was intensified when Flann defeated and slew Maine mac Néill of Uí Chernaig.
[4] In 714 Flann fought the Battle of Bile Tened (near Moynalty with the Clann Cholmáin led by Murchad Midi (died 715).