Dermot MacMurrough (Diarmait Mac Murchada) was a Gaelic lord and king of Leinster. He married his second wife, Mór, c. 1152 and they had two children, Aoife and her brother Conchobar.
Dermot was an ambitious man who was eager to extend his territory, resulting in many battles, abductions and power struggles over the years. He was eventually banished from Ireland as punishment for abducting his rival’s wife, Derbfhorgaill. In 1168 he sought Strongbow’s assistance in regaining his power in Ireland, and offered him his daughter’s hand in marriage. After Dermot’s death in 1171 the kingship of Leinster went to Strongbow.
The most contemporary sources for information on Dermot and his arrangements with Strongbow are Expugnatio Hibernica (The Conquest of Ireland) written by Giraldus Cambrensis in the twelfth century, and The Song of Dermot and the Earl, a French narrative poem, written in the late twelfth century. Geraldus describes Dermot as “…tall and well built, a brave and warlike man among his people, whose voice was hoarse as a result of constantly having been in the din of battle.”
Despite being a patron of the church and founding abbeys at Baltinglass and Kilkenny, Dermot is remembered mostly in a negative light, and is described in his obituary in the Annals of Tigernach as fer buaidhirtha na Banba ocus aidhmillti Erenn (the disturber and the destroyer of Ireland).