Baron Inchiquin

Baron Inchiquin (Irish: Barún Inse Uí Chuinn) is one of the older titles in the Peerage of Ireland. It was one of two titles created on 1 July 1543 for Murrough O'Brien, Prince of Thomond, who claimed descent from Brian Boru, a High King of Ireland. The English titles were granted under the policy of surrender and regrant, and therefore conditional upon the abandonment of any Irish titles, the adoption of English customs and laws, pledging of allegiance to the Crown, apostasy from the Catholic Church, and conversion to the Church of Ireland. Murrough was made both Earl of Thomond in the Peerage of Ireland, with remainder to his nephew Donough O'Brien and Baron Inchiquin, with remainder to his male heirs. Following the death of his first cousin, Conor O'Brien, 18th Baron Inchiquin, in June 2023, he was succeeded by Conor O'Brien, 19th Baron Inchiquin.

On his death in 1551, Murrough was succeeded in the earldom, according to the special remainder, by his nephew, the second Earl (see Earl of Thomond for the later history of this title), but the barony of Inchiquin passed to his son Dermod, the second baron. Dermod's great-great-grandson, the sixth baron, was a prominent military commander during the Irish Confederate Wars (1643–48), first for the English Parliament, then as a Royalist commander during the Cromwellian conquest of Ireland (1649–53) during the Wars of the Three Kingdoms. In 1654 he was created Earl of Inchiquin in the Peerage of Ireland.

He was succeeded by his son, William O'Brien, 2nd Earl of Inchiquin, who served as governor of English Tangier and as Governor of Jamaica. His son, William O'Brien, 3rd Earl of Inchiquin, became Governor of Kinsale in 1693. The fourth earl, also named William O'Brien, represented Windsor, Camelford and Aylesbury in the British House of Commons.

The fifth earl, Murrough O'Brien, was the nephew and son-in-law of his predecessor. In 1800, he was created Marquess of Thomond in the Peerage of Ireland, with remainder to his brother, the Honorable Edward Dominic O'Brien, a captain in the British Army. The following year he was made Baron Thomond of Taplow in the County of Buckingham in the Peerage of the United Kingdom to allow him to sit in the House of Lords, with remainder to the male heirs of his body. He died without male issue in 1808, when the barony of Thomond became extinct.

He was succeeded in the marquessate according to the special remainder, and in the other Irish titles, by his nephew William O'Brien, 2nd Marquess of Thomond, the third son of the aforementioned Captain Edward O'Brien. The second marquess was an Irish representative peer. In 1826 he was created Baron Tadcaster of Tadcaster in the County of York in the Peerage of the United Kingdom. He had no sons and on his death in 1846 the barony of Tadcaster became extinct.

He was succeeded in the Irish peerages by his younger brother, James O'Brien, 3rd Marquess of Thomond, an admiral in the Royal Navy. He had no sons and on his death in 1855 the marquessate and earldom of Inchiquin became extinct.

In 1855, he was succeeded in the barony of Inchiquin by his distant relative Sir Lucius O'Brien, 5th Baronet, who became the 13th Baron Inchiquin. The O'Brien Baronetcy, of Leaghmenagh in the County of Clare, had been created in the Baronetage of Ireland in 1686 for Donough O'Brien, who had earlier represented County Clare in the Irish House of Commons. He was the great-great-grandson and namesake of Donough O'Brien (died 1582), younger son of the first Earl of Thomond and first Baron Inchiquin. His grandson, the second baronet, great-grandson the third baronet, and great-great-grandson the fourth baronet, also represented County Clare in the Irish Parliament, with the fourth baronet also representing Ennis. The latter was succeeded by his son, the fifth baronet.

Before becoming the 13th Baron, the fifth Baronet O'Brien had represented County Clare in the House of Commons and was later an Irish Representative Peer. He also served as Lord Lieutenant of County Clare. He was succeeded by his son, Edward O'Brien, 14th Baron Inchiquin, also an Irish Representative Peer and Lord Lieutenant of County Clare. His son, Lucius O'Brien, 15th Baron Inchiquin, also sat in the House of Lords as an Irish Representative Peer, and also served in the British military and had been appointed High Sheriff of Clare in 1898, and justice of the peace of Salop.