Tigernan Ua Ruairc

Tighearnán Mór Ua Ruairc (older spelling: Tigernán Mór Ua Ruairc), anglicised as Tiernán O'Rourke (fl. 1124–1172) ruled the Kingdom of Bréifne as the 19th king in its Ua Ruairc (later O'Rourke) dynasty (964–1605 CE). He was a descendant of Ui Riagain, and one of the provincial kings in Ireland in the twelfth century, constantly expanding his kingdom through shifting alliances, of which the most long-standing was with Toirdelbach Ua Conchobair King of Connacht and High King of Ireland, and subsequently his son and successor Ruaidhri Ua Conchobair. He is known for his role in the expulsion of Diarmait Mac Murchada, King of Leinster, from Ireland in 1166. Mac Murchada's subsequent recruitment of Marcher Lords to assist him in the recovery of his Kingdom of Leinster ultimately led to the Norman Invasion of Ireland.

Ua Ruairc may have ruled Bréifne as early as 1124, as indicated in Mac Carthaigh's Book and the Annals of the Four Masters, the former indicating he allied at the time with the kings of Meath and Leinster against Toirdelbach Ua Conchobair. However the Annals of Ulster and the Annals of Tigernach do not mention him until 1128, where they record his robbing and killing of some of the Archbishop of Armagh's company, the former calling it 'A detestable and unprecedented deed of evil consequence'.

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