Clinton served in Canada during the war of the Austrian succession and in Germany during the seven years’ war. He was a cousin of Henry, 2nd Duke of Newcastle, and was returned on the Newcastle interest at Boroughbridge and Newark. In the House of Commons he was a regular Government supporter. From 1775 to 1782 he was in America, holding military posts of crucial importance. He seems to have been unequal to his responsibilities. ‘Though I believe him ... a brave and honest man’, wrote G. B. Rodney to Germain, 22 Dec. 1780,
Clinton voted against Shelburne’s peace preliminaries, 18 Feb. 1783, and supported the Coalition. In July 1783 North applied to the King for an Irish viscountcy for Clinton, but could only obtain his agreement to a barony. Whereupon, William Windham reported to Lord Northington, the lord lieutenant, 17 July, Clinton ‘was understood to have refused his peerage, not being able to succeed as to being a viscount’.
After his return to England Clinton pressed for an inquiry into his conduct as commander-in-chief in America; on this being refused him, he published a pamphlet for his own justification, and wrote but never published a more elaborate apologia.
Clinton died 23 Dec. 1795.
