The O’Briens are an illustrious and prominent clan that has shaped the history of Ireland. The name, also spelled O’Bryan or O’Brian, means “of Brian” indicating descendance from Brian Borumha mac Cennetig, or Brian Boru, the celebrated High King of Ireland.
Brian Boru (925-1014) received the throne of Thomond (an area which covers much of modern day County Clare as well as parts of Limerick and Tipperary) after his elder brother, Mathgamain, was killed in 976. By 1002, he had attained the title of High King of Ireland, subjugating all the other kings in Ireland under his rule.
The King of Leinster Máelmorda mac Murchada, aided by the Dublin Vikings, rebelled against Brian’s rule. The two armies met on the field of Clontarf (now a suburb of Dublin) in 1014. Brian Boru’s army won, but at the cost of Boru’s life.