Diarmait Mac Murchada

So the inevitable invasion of Ireland by the Anglo-Norman forces of King Henry II of England was initiated by an invitation from Diarmait Mac Murchada (anglicized as Dermot MacMurrough), the one-time King of Leinster. The illustration of him here is from a copy of Gerald of Wales' Expugnatio Hibernica ("Conquest of Ireland").

Diarmait (c.1110 - May 1171) had an illustrious background. His father, Donnchadh, was King of Leinster. His great-grandmother was descended from Brian Boru. His father died while attacking the King of Dublin in 1115; succession passed to Diarmait's older brother, Enna. When the brother died in 1126, the 16-year-old Diarmait became king.

This was not welcomed by the then-High King of Ireland, Toirdelbach Ua Conchobair (Turlough O'Conor), who saw Diarmait as a potential rival. Turlough sent an ally, Tigernán Ua Ruairc (Tiernan O'Rourke), King of Meath, to harry Leinster and oust Diarmait. Tiernan started slaughtering Leinster livestock to starve the inhabitants. Diarmait was ousted, but Leinster clans brought him back in 1132, where he remained for almost 40 years.

Between 1140 and 1170, Diarmait built Abbeys at Fern and Baltinglass, Killeshin Church, and St. Saviour's Priory. He sponsored numerous convents. He also had two wives—not in succession but concurrently, as allowed in early Irish/Brehon law. (This was another reason why the Roman Church wanted stronger influence in Ireland.) His first wife was the mother of a son who later succeeded Diarmait. His second wife was the mother of a daughter, Aoife.

There was a rumor that Diarmait kidnapped Tiernan's wife, aided by Tiernan's brother who wanted Tiernan out of the way and his kingship of Meath up for grabs. Tiernan must have had issues getting along with others, since the High King actually used Diarmait's help much later to raid Tiernan's lands because Tiernan had become problematic.

In 1166, a different High King was defeated by Ruaidrí Ua Conchobair (Rory O'Conor), who deposed Diarmait by sending Tiernan (again!) to Leinster. Diarmait fled to Wales and sought support from King Henry. Henry did not wish to get directly involved, but gave permission for Diarmait to seek help from the nobility. One who agreed to help was the 2nd Earl of Pembroke, Richard de Clare, to whom Diarmait promised his daughter Aoife (Eva of Leinster) in marriage (and the kingship of Leinster after Diarmait's death).

So began the Norman invasion of Ireland. The military aid was so useful that Diarmait used it to expand his territory to Thomond. Initially it was a Cambro-Norman invasion because it was begun by Welsh lords, but it was soon followed by the Anglo-Norman invasion when Henry's own forces arrived to subdue the island and make sure the Norman lords knew to whom they owed allegiance.

One of the "beneficiaries" of the invasion was the Roman Church, allowing it to bring the Irish Church into conformity. One of the facets of Irish culture that the Church wanted to "fix" was the law that allowed Diarmait to have two wives. This Brehon Law is worth exploring further, and we will do just that next time.