Deaths on May 1

Diarmait Mac Murchada, King of Leinster (b. 1110)

Diarmait Mac Murchada (Modern Irish: Diarmaid Mac Murchadha), anglicised as Dermot MacMurrough, Dermod MacMurrough, or Dermot MacMorrogh (c. 1110 – c. 1 May 1171), was a King of Leinster in Ireland. In 1167, he was deposed by the High King of Ireland, Ruaidrí Ua Conchobair (Rory O'Connor). The grounds for the deposition were that Mac Murchada had, in 1152, abducted Derbforgaill, the wife of the king of Breifne, Tiernan O'Rourke (Irish: Tighearnán Ua Ruairc). To recover his kingdom, Mac Murchada solicited help from King Henry II of England. His issue unresolved, he gained the military support of the 2nd Earl of Pembroke (Richard de Clare, nicknamed "Strongbow"). At that time, Strongbow was in opposition to Henry II due to his support for Stephen, King of England against Henry's mother in the Anarchy. In exchange for his aid, Strongbow was promised in marriage to Mac Murchada's daughter Aoife with 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 English 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.