Diarmait Mac Murchada

Diarmait Mac Murchada (Modern Irish: Diarmaid Mac Murchadha; anglicised as Dermot MacMurrough or Dermot MacMurphy) (c. 1110 – c. 1 May 1171), was King of Leinster in Ireland from 1127 to 1171. In 1167, he was deposed by the High King of Ireland, Ruaidrí Ua Conchobair. To recover his kingdom, Mac Murchada solicited help from King Henry II of England. His issue unresolved, he gained the military support of the Richard de Clare, 2nd Earl of Pembroke (otherwise known as "Strongbow"), thus initiating the Anglo-Norman invasion of Ireland.

In exchange for his aid, Mac Murchada promised Strongbow the hand in marriage of his daughter Aoife and the right to succeed to the Kingship of Leinster. Henry II then mounted a larger second invasion in 1171 to ensure his control over Strongbow, resulting in the Norman Lordship of Ireland. Mac Murchada was later known as Diarmait na nGall (Irish for "Diarmait of the Foreigners"). He was seen in Irish history as the king that invited the first-ever wave of Anglo-Norman settlers, who were planted by the Norman conquest. The invasion had a great deal of impact on Irish Christianity, increasing the de facto ability of the Holy See to regulate Christianity in Ireland. Provided by Wikipedia