Strachan resumed command. On 8 July, whilst off Alicante, the Experiment engaged the French privateer Télémaque. Carrying a similar number of guns, but with 460 men, a far larger crew, the Télémaque attempted to use this massive numerical superiority to come alongside the Experiment and board her. After two failed attempts, the Télémaque managed to briefly come alongside, but only a few Frenchmen made it aboard and were promptly killed. Strachan then brought the Experiment alongside again and ordered Locker to lead a boarding party onto her. Locker capably did so, storming the Télémaque and carrying her. At the end of the engagement, 235 Frenchmen had been killed or wounded, for the loss of only 48 from the Experiment. Locker was one of the casualties, having been wounded in the leg. Despite it being only minor, he never fully recovered from its effects. Both Locker and Strachan were transferred in December 1758 to the 32-gun frigate HMS Sapphire. She was attached to the fleet off Brest through summer and autumn 1759. Whilst aboard her, Locker was present at the defeat of the French at the Battle of Quiberon Bay on 20 November. After this success, Locker went aboard Hawke's flagship HMS Royal George in March 1760, and became the ship's first lieutenant in July 1761. He was promoted to his first command, that of the fire ship HMS Roman Emperor on 7 April 1762. According to his son, Edward Hawke Locker, William Locker considered this the start of his happiest period of naval service. An appointment to command the sloop HMS Nautilus came in 1763, and he was dispatched to withdraw the British garrison from Gorée in West Africa, after the Treaty of Paris restored it to the French. Locker returned the garrison to England and then departed to take up station at Jamaica. Here he visited a number of ports in the Gulf of Mexico, and even ventured up the Mississippi River. The Nautilus was paid off at Deptford on 8 March 1768 and in a gesture of approval of Locker's services, the Admiralty promoted him to captain on 26 May 1768. Locker then commanded the frigate HMS Thames, on the home station. He was her captain from 1770 until 1773. In 1777, he took command of HMS Lowestoffe, sailing her to the West Indies. During this period, one of his lieutenants was the newly promoted Horatio Nelson. Nelson,