Cadogan, William 1601-1661, major of horse under the Commonwealth and governor of Trim, was eldest son of Henry Cadogan of Llanbetter, and great-grandson of Thomas Cadogan of Dunster, Somersetshire, who in his will, dated 12 June 1511, styles himself valectus corone, and is credited by many genealogists with descent from the ancient princes of Wales [see Cadwgan]. William Cadogan was born at Dunster in 1601, and accompanied the Earl of Strafford to Ireland, where he was serving as a captain of horse in 1641. In 1649 he reappears as a major of horse in Cromwell's army in Ireland, and, for his services in the revolted districts round Dublin, and especially against the Irish chieftains Phelim O'Neill and Owen O'Rowe, was rewarded with the governorship of the castle and borough of Trim, co. Meath, which he held until his death, 14 March 1661. A monument to him, stated by some writers to be at Trim and by others in Christ Church, Dublin, bears or bore a lengthy Latin inscription, transcribed in Collins's Peerage, vol. v., which sets forth these and other particulars of him. Cadogan had a son Henry, a barrister settled in Dublin, who married Bridget, daughter of Sir Hardress Waller, and by her had three children. The eldest of them, William, became a distinguished soldier, and was Marlborough's most trusted lieutenant [see Cadogan, William, first earl].
Collins's Peerage (edit. 1812), vol. v.
Contributor: H. M. C. [Henry Manners Chichester]