Field Marshal William Harcourt, 3rd Earl Harcourt, (20 March 1743 – 17 June 1830) was a British nobleman and British Army officer. He served as an aide-de-camp to Lord Albemarle for the expedition to Havana during the Seven Years' War. He also commanded his regiment at the Battle of White Plains and then captured General Charles Lee at Basking Ridge during the American Revolutionary War. After that he commanded the British Cavalry at the Battle of Willems during the Flanders Campaign. He succeeded the Duke of York as commander during that campaign and oversaw the British retreat and their final evacuation from Bremen. His last main military role was as Governor of the Royal Military College at Great Marlow. Military career Born the younger son of Simon Harcourt, 1st Earl Harcourt and Rebecca Harcourt (née Samborne Le Bas), Harcourt was commissioned as an ensign in the First Regiment of Foot Guards on 10 August 1759. He became a captain in the 16th Light Dragoons, a regiment which had been raised at his father's expense and was known as "Harcourt's Black Horse", on 27 October 1759. He transferred to the 3rd Dragoons on 30 June 1760 and was subsequently sent to Mecklenburg-Strelitz (with his father) to escort the consort-elect of King George III to England. In recognition of this mission he was appointed an equerry to the Queen Consort later that year. Harcourt served as an aide-de-camp to Lord Albemarle for the expedition to Havana in 1762 during the Seven Years' War. He was promoted to lieutenant colonel and given command of the 31st Regiment of Foot in November 1764, of the 4th Light Dragoons in April 1765 and of the 16th Light Dragoons in June 1768. In 1766 he was appointed a Groom of the Bedchamber to King George III, a post he held until 1808, when he was made Master of the Robes until 1809, after which he was Master of the Horse to the Queen until 1818. He also sat in Parliament as Member of Parliament for Oxford from 1768 to 1774. He commanded the 16th Light Dragoons at the Battle of White Plains in October 1776 and then captured General Charles Lee at Basking Ridge in December 1776 during the American Revolutionary War. Promoted to colonel on 29 August 1777, he became aide-de-camp to the King in September 1777 and honorary colonel of the 16th Light Dragoons