Dictionary of National Biography, 1885-1900/O'Brien, Charles
O'BRIEN, CHARLES, fifth Viscount Clare (d. 1706), was the son of Daniel, third viscount [see under O'Brien, Daniel, first Viscount Clare], by Philadelphia, daughter of Francis Leonard, lord Dacre. As the Honourable Charles O'Brien he commanded a regiment of foot in James II's army in Ireland during 1689 and 1690, and in 1691 took over a cavalry regiment and served at the second siege of Limerick. On leaving Ireland for France in 1692 he was promoted captain of the gardes du corps, and was subsequently attached to the Queen of England's dragons-à-pied, of which he became colonel on the death of Francis O'Carrol at the battle of Marsaglia on 4 Oct. 1693. His brother Daniel, the fourth viscount, was mortally wounded on the same occasion, and he succeeded to the title. On 8 April 1696 he became colonel of the Clare regiment, so named in honour of his family, and served at Valenza and on the Meuse during the campaigns of 1696 and 1697. On the outbreak of the war of the Spanish succession he joined the army of Germany, was promoted brigadier-general on 2 April 1703, and took a distinguished part in the rout of the imperialists at Hochstädt on 20 Sept. 1703. Promoted major-general early in 1704, he commanded the three Irish regiments of Clare, Lee, and Dorrington at Blenheim, cut his way out of the village of Oberklau, and escaped with his three regiments, in admirable order, to the Rhine (Sevin de Quincy, Hist. Militaire, iv. 280). He was created maréchal-de-camp on 2 Oct. 1704, joined the army of Flanders, and was, eighteen months later, mortally wounded at Ramillies on 23 May 1706. A monument to his memory was erected by his widow in the church of the Holy Cross at Louvain.
O'Brien married Charlotte, eldest daughter of the Hon. Henry Bulkeley; Lady Clare remarried Colonel Daniel O'Mahony [q. v.] at St. Germains in 1712. O'Brien left a daughter, Laura, who married the Comte de Breteuil; and a son, Charles O'Brien, sixth viscount Clare (1699–1761), born on 27 March 1699. The command of the Clare regiment devolved upon its lieutenant-colonel, a kinsman of the Clare family, the gallant Murrough O'Brien, but six thousand livres per annum were set apart by order of Louis XIV, out of the emoluments of the position, for the maintenance of the young viscount. The latter had been enrolled a captain in the French service during his father's lifetime, but did not commence his active military career until 1719, when he joined the French army in Spain. In 1715 he paid a visit to England, and was presented to George I, who offered to procure him the reversion of the title and estates of his relative, the Earl of Thomond, provided that he would enter the English service and would change his religion; but with these conditions O'Brien refused to comply. He returned to France, excited the admiration of George II by his conduct at Dettingen, and bore a distinguished part in the French victories at Fontenoy, where the behaviour of the Irish brigade turned the fortune of the day, and at Roucoux and Laffeldt. He was created a marshal of France on 24 Feb. 1757, and was known as Maréchal Thomond, having assumed the title of Comte de Thomond upon the death of Henry, eighth earl of Thomond, in 1741. He died at Montpellier, during his tenure of the command-in-chief of the province of Languedoc, on 9 Sept. 1761. By his wife, Marie Geneviève Louise Gauthier de Chiffreville, he left a son Charles, colonel of the Clare regiment, who died at Paris, without issue, on 29 Dec. 1774.
[Burke's Extinct Peerage, p. 407; G. E. C.'s Peerage, s. v. Clare; O'Hart's Irish Pedigrees, 1887, i. 167–8; Webb's Compendium of Irish Biogr. p. 366; O'Callaghan's Irish Brigades in the Service of France, pp. 38–44; O'Conor's Military History of the Irish Nation, pp. 290, 316; D'Alton's King James's Irish Army List, p. 315; O'Donoghue's Historical Memoirs of the O'Briens, pp. 348–74.]