INCHIQUIN, MURROUGH O'BRIEN, 1ST EARL OF (c. 1614- 1674), Irish soldier and statesman, was the son of Dermod O'Brien, 5th Baron Inchiquin (d. 1624). He belonged to a great family which traced its descent to Brian Boroimhe, king of Ireland, and members of which were always to the forefront in Irish public life. The first baron of Inchiquin was another Murrough O'Brien (d. 1551) who, after having made his submission to Henry VIII., was created baron of Inchiquin and earl of Thomond in 1543. When Murrough died in November 1551 by a curious arrangement his earldom passed to his nephew Donogh, son of Conor O'Brien (d. 1539), the last independent prince of Thomond (see THOMOND, EARLS OF), leaving only his barony to be inherited by his son Dermod (d. 1557), the ancestor of the later barons of Inchiquin.
Murrough O'Brien, who became 6th baron of Inchiquin in 1624, gained some military experience in Italy, and then in 1640 was appointed vice-president of Munster. He took an active and leading part in suppressing the great Irish rebellion which broke out in the following year, and during the Civil War the English parliament made him president of Munster. Early in 1648, however, he declared for his former master Charles I., and for about two years he sought to uphold the royalist cause in Ireland. In 1654 Charles II. made him an earl. His later years were partly spent in France and in Spain, but he had returned to Ireland when he died on the 9th of September 1674.
His son William, the 2nd earl (c. 1638-1692), served under his father in France and Spain, and for six years was governor of Tangier. He was a partisan of William III. in Ireland, and in 1690 he became governor of Jamaica where he died in January 1692. In 1800 his descendant Murrough, the sth earl (d. 1808), was created marquess of Thomond, but on the death of James, the 3rd marquess, in July 1855 both the marquessate and the earldom became extinct. The barony of Inchiquin, however, passed to a kinsman, Sir Lucius O'Brien, Bart. (1800-1872), a descendant of the first baron and a brother of William Smith O'Brien (q.v.).
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)