When the American Revolutionary War broke out, Hunter served under Howe for the duration of his time in command, acting virtually as master of the fleet. He was active in the Chesapeake raid and the expeditions on the Delaware, as well as the defence of Sandy Hook. On Howe's recall, his reputation by now stale with the Sandwich administration, Hunter was not able to have his request to be made lieutenant honoured. Instead he joined the 74-gun as a volunteer in 1779, under her captain, Keith Stewart. He was appointed lieutenant of HMS "Union" by Sir Charles Hardy, but the Admiralty refused to confirm the appointment and Hunter returned to the "Berwick" as a volunteer in 1780, and went out the West Indies. There he received a commission from the commander in chief, Sir George Rodney. Hunter returned to England aboard the "Berwick" in 1781, and was present at the Battle of Dogger Bank on 5 August that year. Howe appointed him third lieutenant of his flagship in 1782, and was advanced to first lieutenant by the time she took part in the relief of Gibraltar and the Battle of Cape Spartel. Following these engagements Hunter was appointed to his first command, that of the 14-gun sloop HMS "Marquis de Seignelay", on 12 November 1782.