HIS STORY & TIMELINE
Upon replacing his father as King of Leinster, Dermot mac Murrough embarked on several battles with kings looking to oust him, most notably Tiernan O’Rourke, the King of Breifne (Leitrim and Cavan), and Rory O’Connor, the last King of Ireland. These battles resulted in mac Murrough being overthrown as King of Leinster, with him eventually fleeing Ireland for several years to live in Wales, England and France. Dermot eventually returned to Ireland and his position as King of Leinster some years later.
MacMurrough was born around 1100 and was the son of Donnchad MacMurrough, the king of both Dublin and Leinster. Dermot was a descendant of Brian Boru, with his father being grandson of Boru's granddaughter, Dervorgilla. Dermot's father died in 1115 in a battle with his cousin, Sigtrygg Silkbeard, the Viking king of the Dublin.
Following the death of his older brother Énna in 1126, Dermot became the King of Leinster. He became a feared rival of the then King of Ireland, Turlough Mór O'Connor, who sent one of his allied kings Tiernan O'Rourke to oust MacMurrough and take over Leinster. This resulted in a brutal campaign in which many livestock was slaughtered, and ultimately led to the dethroning of MacMurrough.
Dermot called on the help of several Leinster clans and was able to regain control of Leinster and return to the throne in 1132. This resulted in up to 20 years of tension and battles between Dermot and the then King of Ireland, Turlough Mór O'Connor.
Following the death of Dermot's ally Muircheartach Mac Lochlainn (King of Ireland from 1156 - 1166), MacMurrough was deposed from his throne by his arch enemy Tiernan O'Rourke, and the new king of Ireland, Rory O'Connor. MacMurrough fled Ireland to seek help from Henry II, a decision that would ultimately result in the end of Irish kingship, and the introduction of British rule in Ireland for several centuries. This earned Dermot the nickname of “Dermot na nGall” translated as “Dermot of the Foreigners”.
Strongbow launched an attack on Leinster from his base in Wales, and duly captured Waterford and Dublin, ensuring MacMurrough would once again become King of Leinster. Dermot had previously captured Wexford in 1167 in preparation for the invasion from Strongbow. Dermot rewarded Strongbow with the hand of his daughter Aoife in marriage.
Dermot MacMurrough is believed to have died in 1171 with Strongbow replacing him as King of Leinster. MacMurrough was buried at Ferns Abbey in Wexford, an abbey that he founded in 1158.