He laid waste the country as far as Sliab Monduirn in Brega .
Muiredach retaliated and led a force to attack the lands of the southern Ui Neill in 875 .
Muiredach laid waste the country as far as Sliab Monduirn in Brega .
Muiredach retaliated and led a force to attack the lands of the southern Ui Neill in 875 .