Flaithbertaigh would then take part in campaigns against the Cenél Chonaill in 1011 alongside Brian's sons Murchad and Domnall. However, they were unsuccessful in gaining the submission of the Cenél Chonaill. Brian proceeded to then personally lead a second invasion later that year, this time successfully subjugating and receiving the submission of the Cenél Chonaill. While Flaithbertaigh would continue attacking the Ulaid and Cenél Chonaill in late 1011 and in 1012, for the time he was no longer of any threat to Brian.