1911 Encyclopædia Britannica/Thomond, Earl and Marquess of
THOMOND, EARL AND MARQUESS OF, Irish titles borne by the great family of O'Brien, the earldom from 1543 to 1741 and the marqucssate from 1800 to 1855. Thomond, or Tuaidh-Muin, was one of the three principalities of Munster, forming the northern part of the province. Its earls were descended from Turlough O'Brien (c. 1009-1086), king of Munster, and through him from the celebrated king of Ireland, Brian Boroimhe. Turlough's descendants, Conchobhar O'Brien (d. 1267) and Brian Ruadh O'Brien (d. 1276), kings of Thomond, were both typical Irish chieftains. Conchobbar's tomb and effigy with a crown are still to be seen in the ruined abbey of Corcomroe, Co. Clare. His descendant Conor O'Brien (d. 1539), prince of Thomond, took part in the feud between the great families of Fitzgerald and Butler and was the last independent prince of Thomond. It is interesting to learn that in 1534, when he was in some straits, he wrote to the emperor Charles V. offering to submit to his authority. Conor's brother, Murrough O'Brien (d. 1551), prince of Thomond, the succeeding chief of the race, gave up his " captainship, title, superiority and country " to Henry VIII. in 1543, when he was created earl of Thomond. By special arrangement the earldom descended, not to his son Dermod, but to his nephew, Donough, who became the 2nd earl. Dermod, however, inherited the barony of Inchiquin, which was conferred upon his father at the same time as the earldom.
Conor O'Brien, the 3rd earl (c. rs34-c. 1582), was for some years at the outset of his career, harassed by the attacks of his discontented kinsmen. Then in his turn he rose against the English, but was defeated and fled to France; in 1571, however, he was pardoned and formally surrendered his lands to Elizabeth. One of his younger sons was Daniel O'Brien (c. 1577-c. 1664) who, after loyally serving Charles I. and Charles II., was created Viscount Clare in 1663. His grandson Daniel, the 3rd viscount (d. 1691) served James II. in Ireland, being outlawed and deprived of his estates by the English parliament. The three succeeding viscounts Clare all distinguished themselves in the service of France. Daniel, the 4th viscount, was mortally wounded at the battle of Marsaglia in 1693; his brother Charles, the 5th viscount (d. 1706), was killed at the battle of Ramillies; and the latter's son Charles, the 6th viscount (16991761) after a brilliant military career, was made a marshal of France in 1757. When Charles, the 7th viscount, died in 1774 the title became extinct.
Donough O'Brien, the 4th earl (d. 1624), called the "great earl," was the son and successor of the 3rd earl. He served England well in her warfare with the rebellious Irish during the closing year of Elizabeth's reign and was made president of Munster in 1605. He had two sons, Henry, the 5th earl, (d. 1639) and Barnabas, the 6th earl (d. 1657). During the Irish rebellion of 1640-41 Barnabas showed a prudent neutrality, and then joined Charles I. at Oxford, where in 1645 he was created marquess of Billing, but the patent never passed the great seal and the title was never assumed. The succeeding earls were Barnabas's son Henry (c. 1621-1691) and Henry's grandson Henry (1688-1741) who was created an English peer as Viscount Tadcaster. When he died the earldom of Thomond became extinct.
The estates of the earldom descended to the last earl's nephew, Percy Wyndham (c. 1713-1774), a younger son of Sir William Wyndham, Bart. He took the additional name of O'Brien and was created earl of Thomond in 1756. When he died unmarried the title again became extinct.
In 1800 Murrough O'Brien, 5th earl of Inchiquin (c. 17241808), was created marquess of Thomond. He was succeeded by his nephew William (c. 1765-1846) who was created a British peer as Baron Tadcaster in 1826. His brother James, the 3rd marquess (c. 1768-1855), was an officer in the navy and became an admiral in 1853. When he died the marquessate became extinct.
See John O'Donoghue, Historical Memoirs of the O'Briens (Dublin, 1860).