the ship formed part of the naval escort that brought Charlotte of Mecklenburg-Strelitz to England for her marriage to George III, arriving at Harwich on 6 September. Stewart was promoted to post-captain on 7 April the following year because of a demand from his father as part of political negotiations, but the historians Brian Vale and Griffith Edwards note that Stewart was also a highly competent seaman and not himself overtly ambitious. He was appointed to the 20-gun post ship HMS Lively. He commanded the ship on the West Indies Station until the end of the Seven Years' War. Stewart then sailed to the North America Station before returning to Britain. After a period of service in British waters, in June 1763 he went out in Lively to the Mediterranean Sea. Around this time Stewart also became the first patron of William Bligh, who would occasionally serve under him throughout his career. Stewart commanded in the Mediterranean until Lively was paid off on 21 February 1765 for extensive repairs. On 16 March he was instead given command of the 32-gun frigate HMS Montreal, also in the Mediterranean, in which he continued until 6 March the following year. American Revolutionary War Stewart was not given another command for a considerable period of time after this, choosing instead to focus on his political career. This situation changed with the start of the American Revolutionary War, and he was appointed to command the brand new 74-gun ship of the line HMS Berwick on 27 December 1777. Serving in the English Channel, he fought at the Battle of Ushant on 27 July the following year. Stationed in the vanguard division of the British fleet, Berwick was heavily engaged during the battle and had ten men killed. Afterwards Berwick continued to serve in the English Channel, and was part of the fleet that relieved Guernsey in September 1779. While Berwick was still at sea disagreements between the two commanders of the British at Ushant, Admiral Augustus Keppel and Vice-Admiral Sir Hugh Palliser, had led to political controversy. The First Lord of the Admiralty at the time, John Montagu, 4th Earl of Sandwich, specifically noted that: With his ship having received a refit in December, Stewart was sent with Berwick to the West Indies on 8 April 1780, in a force commanded by Commodore Robert Boyle-Walsingham. Serving at Jamaica from 12 July, Berwick was one of