 Even before Diarmait 's demise , the Uí Chennselaig began to fight amongst themselves in a struggle that was almost certainly an after @-@ effect of Diarmait 's sons ' untimely deaths . Specifically , the Annals of the Four Masters , and the Annals of Inisfallen reveal that Domnall battled against the forces of his own first cousin once removed , Donnchad mac <unk> <unk> ( died <unk> ) , before Diarmait 's ally , Toirdelbach Ua Briain , King of Munster ( died 1086 ) , was able to intervene and restore order in the Kingdom of Leinster . 
