Cadogan, William (1672–1726), 1st Baron and Earl Cadogan , soldier, was born at Liscartan, Co. Meath, eldest son of Henry Cadogan (1642–1714), barrister, of Liscartan and Dublin, and Bridget Cadogan, daughter of Sir Hardress Waller (qv); his grandfather was William Cadogan (1601–61; (qv)). Educated at Westminster and TCD (admitted 28 March 1687), he joined Wynne's Inniskilling dragoons and in the wars against France became perhaps the most distinguished British soldier after John Churchill (qv), duke of Marlborough, whom he served in many capacities (quartermaster-general and chief of staff, cavalry leader and field commander, chief of intelligence and negotiator) and succeeded as commander-in-chief and master-general of the ordnance (1722). The range of his abilities was shown in 1708–9 by his seizure and exploitation of the Oudenarde bridgehead, his successful management of the ‘Great convoy’ (100 siege pieces, nearly 17,000 horses, and 90,000 men), and a lone reconnaissance of enemy territory, in disguise. His overbearing manner and exactions for personal gain, however, are said to have jeopardised allied standing in Flanders.
Cadogan served as envoy to Hanover (1706), the Hague (1706–10, 1714–20), and other capitals in maintaining alliances and negotiating the ‘barrier treaties’; he was also in charge of supplying troops and conducting operations in Scotland during the 1715 rebellion. Cadogan was chosen by Marlborough as whig MP for Woodstock, Oxon., and held the seat 1705–16. He was created Baron Cadogan of Reading 21 June 1716 and Earl Cadogan of Denbigh 8 May 1718; among other offices and honours, he was lieutenant of the Tower of London (1706–13), master of the robes (1714–26), and governor of the Isle of Wight (1715–26); and a lord justice during George I's absence from England. He married (23 March 1704) Margaretha Cecilia Munter (1675–1749), of the Amsterdam noblesse de la robe; their two daughters married the duke of Richmond and Count Bentinck. He built the mansion of Caversham, Oxon. (1718–20); his houses and estates in Dublin, Meath, and Limerick were sold in 1720–22. He died ‘in top dress’ at his house at Kensington Gravelpits, Surrey, 17 July 1726, after an operation, and was buried in Westminster abbey.