The O'Rourkes were part of the large tribal grouping of the Ui Briuin, claiming common descent from Brion, a fifth-century King of Connacht, together with such other prominent families as the O'Connors and MacDermotts (Ui Briuin Ai), and the O'Flahertys (Ui Briuin Seola). Along with the O'Reillys, the O'Rourkes formed the Ui Briuin Breifne. In the early middle ages, the O'Connors and the O'Rourkes were engaged in a long and bloody struggle for supremacy in Connacht, a struggle which ended in the victory of the O'Connors.
The Ruarc from whom the surname derives was a ninth-century King of Breifne, an area covering most of the modern counties of Leitrim and Cavan, along with part of Co. Longford. The first to use his name as part of a hereditary surname was his grandson, Sean Fearghal O Ruairc, who died in 964. Over the following century and a half, four O'Rourkes were Kings of Connacht, and the family became one of the most powerful in Ireland. After the twelfth century, they appear to have accepted the overlordship of the O'Connors, however reluctantly. They also had persistent problems with the other pre-eminent family of Breifne, the O'Reillys, which ultimately resulted in their territory being much reduced. The main stronghold of the family was at Dromahaire, on the shores of Lough Gill in Co. Leitrim.
In common with most of the other ruling families of Gaelic Ireland, the O'Rourkes lost all of their possessions in the great upheavals of the sixteenth and seventeenth centuries. Many of the senior members of the family were part of the great migration of the native aristocracy to mainland Europe, with O'Rourkes particularly prominent in the armies of France, Austria and Russia. In Ireland, of course, the surname remained widespread and popular, concentrated especially in the areas covered by the old kingdom of Briefne. And, despite the departure of so many, the line of descent from the last Chief of the Name, Brian Ballagh O'Rourke, who was inaugurated in 1529 and died in 1562, remains intact. The present holder of the title "O Ruairc of Breifne", recognised as Chief of his Name by the Chief Herald of Ireland is Philip O Rorke, resident in London.
The arms illustrated are those of O Ruairc of Breifne. The Irish crown in the crest is a familiar symbol of royalty, showing the family's kingship in Breifne. The two lions on the shield may be a reminder of the dual nature of that kingship, with command shared between a Taoiseach and Tanaiste. The family motto BUADH means simply "victory", and is an example of a traditional warcry transposed into heraldry, a reminder that the original purpose of arms would have been purely military.
General Count Iosif Kornilievich O Rourke (1772-1849), a nephew of John O Rourke Prince of Breifne (b. 1735), was one of the Russian generals who defeated Napoleon. Many other members of the family were also prominent in Tsarist Russia. Count Edward O Rourke, another member of the family, was Bishop of Danzig before the Second World War.