The son of George Clinton, a naval officer and administrator, Henry joined the New York militia in 1745 as a lieutenant. He went to London in 1749 and was commissioned in the British army in 1751. He was wounded (1762) in the Seven Years' War in Europe and was promoted to major general in 1772. He went to North America in 1775 as second in command to Sir William Howe. He fought with distinction at Bunker Hill and Long Island and was left in command in New York when Howe went south to Pennsylvania. On Howe's retirement (1778), Clinton (knighted 1777) succeeded to the supreme command. He led the main body of his army in an offensive in the Carolinas in 1780. After Charleston fell, he returned to New York, leaving Lord Cornwallis, his second in command, in charge of the subsequent operations that led to the capitulation at Yorktown and the peace treaty recognizing American independence. Clinton resigned his command in 1781 and went back to England, where he found Cornwallis viewed with sympathy and himself blamed for the Yorktown defeat. His Narrative of the Campaign of 1781 in North America (1783) provoked an angry reply from Cornwallis.