In 1167, Diarmaid Mac Murchadha was deprived of his kingdom by the High King of Ireland – Ruaidri Ua Conchobair. The grounds for the dispossession were that Mac Murchada had, in 1152, abducted Derbforgaill, the wife of the King of Breifne, Tiernan O’Rourke. To recover his kingdom, Mac Murchada solicited help from King Henry II of England. In return, Mac Murchada pledged an oath of allegiance to Henry, who sent troops in support. As a further thanks for his reinstatement, Mac Murchada’s daughter Aoife was married to Richard de Clare, the 2nd Earl of Pembroke (nicknamed “Strongbow”). Henry II then mounted a larger second invasion in 1171 to ensure his control over Strongbow, resulting in the Lordship of Ireland, marking the beginning of eight centuries of English dominance.

Mac Murchada was later known as Diarmait na nGall (Irish for Diarmait of the Foreigners) and is often considered to have been the most notorious traitor in Irish history.

Strongbow was his (disputed) successor (MacMurrough’s remaining legitimate son, Connor, was executed while a hostage of Rory O’Connor).

In the play The Dreaming of the Bones by W. B. Yeats, the ghosts of Dermot and Derbforgaill rescue an Irish freedom fighter during the Easter Week rebellion, and reveal that they are bound until an Irishman can forgive them for bringing the English to Ireland.

Image | Ferns Castle, Co Wexford