 In 1052 , Domnall 's aforesaid grandfather conquered the Kingdom of Dublin from Echmarcach mac Ragnaill , King of Dublin and the Isles ( died 1064 / 1065 ) , and soon after appointed Murchad as King of Dublin . About a decade later , Murchad appears to have driven Echmarcach from Mann , after which he gained the kingship of the Isles . Diarmait 's deep @-@ rooted authority in Norse @-@ Gaelic Dublin lasted for two decades , and was a remarkable achievement that no other Irish king had ever accomplished . Unfortunately for the Uí Chennselaig , two of Diarmait 's sons — Murchad and <unk> <unk> — unexpectedly <unk> their father in 1070 , and Diarmait himself fell in battle two years later . 
