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 in October 1779. He bought St Leonard's Hill in Clewer from the Duke of Gloucester in 1781 and, having been promoted to major-general on 20 November 1782, he was then appointed Deputy Ranger of Windsor Great Park.