O'Brien is a surname of Irish origins meaning descendant of Brien (the Brien in this case being Brian Boru). O'Brien is in Irish Ó Briain, from the personal name Brian. The meaning of this is problematic. It may come from bran, meaning "raven", or, more likely, from Brion, a borrowing from the Celtic ancestor of the Welsh which contains the element bre-, meaning "hill" or "high place". By association, the name would then mean "lofty' or "eminent". Whatever the initial meaning of the word, the historic origin of the surname containing it is clear. It simply denotes a descendant of Brian Boramha Boru, "Brian of the Tributes", High King of Ireland in 1002, and victor at the Battle of Clontarf in 1014. Brian was member of the relatively obscure Ui Toirdealbhaigh, part of the Dal gCais tribal grouping based in the Clare/Limerick area. The O'Brien name will be forever linked with the town of Killaloe because it was there that Brian Boru had his palace of Kincora, "Ceann Cora'dh". He was the grandson of Lorcan and the son of MacCinneide (Kennedy and his wife Bebinn). Their home was near the mountain called Slieve Beragh, where the guardian spirit of his tribe, the banshee Arval was said to watch over them from her lofty brooding crag.. Lough Derg was nearby as was the River Shannon. He was educated at Clonmacois. In 959, his father was crowned king on the Rock of Cashel.
The traditional inauguration site of the, O'Briens is outside the village of Quin at a place called Magh Adhair. All that remains is a large mound of earth but to the discerning eye of the historian or genealogist traces of former glory can still be seen.
Having secured control of the Dal gCais in 976, Brian defeated and killed the Eoghanacht king of Munster two years later, and proceeded to wage deadly war against the kingdoms of Connacht, Meath, Leinster and Breifne. Eventually he secured submission (and tributes) from all but the northern Ui Neill, the Leinsterman and the Vikings. His victory at Clontarf united all of Ireland, nominally at least, under a single leader, though Brian himself was slain. The first individual clearly to use O'Brien as a genuinely hereditary surname was Donogh Cairbre O'Brien, son of the king of Munster, Donal Mor. His descendants split into a number of branches, including the O'Briens of Aherlow, the O'Briens of Waterford, the O'Briens of Arra in north Tipperary, and the O'Briens of Limerick, where the surname is perpetuated in the name of the barony of Pubblebrien.
Sometime between 1206 and 1216 Donnchadha Cairbreach O'Brien established his capital in Ennis - now the principal town in Clare. In 1247 this same O'Brien gave shelter to some wandering friars and they proceeded over the years to build the magnificent Ennis Abbey (now a ruin).
The Inchiquin Tomb here houses the bodies of King Turlough O'Brien who died in 1306, Murrough who died in 1551 and the later Barons of Inchiquin. In 1460 Bishop Donnchadha O'Brien of Killaloe (now the cathedral town of Clare) was killed here by Brian O'Brien.
The O'Briens were of the clan of Dal gCais as were many other powerful Claremen. Originally to be a Dalcassian meant that you came from the area around the border of Clare and Tipperary but nowadays it is used to cover all of County Clare.
The O'Brien name is also famous for its association with Maire Rua McMahon who first married a Neylon of Dysert O'Dea and on his death married Conor O'Brien who was killed by Parliamentary forces in 1651. This Maire Rua O'Brien is the stuff of legends as she is remembered in the countryside for her outstanding courage and also for her temper. She is reputed to have hung her maidservants by the hair and her menservants by the neck from the corbels of her castle. She always rode a black stallion who objected to anyone else on his back. Legend says that Maria Rua used to get rid of unwanted suitors by letting them ride the horse at great speed to the 700 foot high Cliffs of Moher, here the horse would stop suddenly and you can guess the rest. Maria Rua's ghost is supposed to be imprisoned in a hollow tree on the avenue of Carnelly House in Clarecastle. Visit there on a windy night if you dare!
From the "Annals of the Four Masters"
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