Research Notes:

King of Leinster. The Annales Cambriæ record that "Diermit rex filius Murcath" was expelled from Ireland by his people and went to the English king, recording in later passages that he returned to Ireland and built "castellum Carrec iuxta Wisefordiam" in 1170, and died in 1172. "Diarmicius Rex Lageniensium" donated "terram…Balidubgaill" to All Saints Dublin by undated charter witnessed by "…Enna filio meo…". The Annals of Tigernach (Continuation) record that Henry II King of England arrived in Ireland in 1171, went to Dublin where he received “the kingship of Leinster and of the men of Meath, Brefne, Oriel and Ulster”.

The Expugnatio Hibernica records the death "apud Fernas circa kal Mai" of "Dermitius Murchardi filius" [in 1171]. ²

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He abducted the wife of his rival for the kingdom of Meath, Tiernan O'Rourke [Tighernán Ua Ruairc], King of Breifne, sealing the hatred between these two kings before 1166. He saw his kingdom invaded by Ruairi O'Connor [Ruadrí Ua Conchobair] of Connacht, and Tiernan O'Rourke, on the death of the high-king Muirchertach MacLochlainn, Diarmat's greatest ally and protector, and on this occasion the Ostmen (Norsemen) of Dublin also participated, and he was ousted from his kingship in Leinster in 1166. He returned to Ireland with a small force of Welsh and Flemish under Richard FitzGodebert, and along with native Irish support to regain control of his homeland, Ui Ceinnsealaigh in southest Leinster, Dermot attempted to reclaim his kingship of Leinster in 1167. ³

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He solicited succor from the Norman King Henry II in 1168. He was defeated southest of Carlow town by the high-king Ruairi O'Conor and his ally Tiernan O'Rourke in 1168 in Carlow town. He recaptured Wexford from the Norse-Irish with the assistance of the Normans under Robert fitz Stephen and Maurice de Prendergast circa 5 May 1169. He arrived in Waterford, after Richard de Clare, aka Strongbow, had taken the town, on 25 August 1170. ^{4 5}