, at which Forrest commanded
HMS Augusta|alt=Depiction of the Battle of Cap-Français with two groups of ships firing their guns at each other In 1755 he commanded , in which he was again sent to the West Indies, and in 1757 was moved into the 60-gun . In October he was detached, with and
Edinburgh under his command, to cruise off
Cap-Français; and on 21 October he encountered a French squadron of four
ships of the line and three heavy frigates under
Guy François de Coetnempren, comte de Kersaint, which came out of harbour to drive the British away from a convoy. After a short conference with his colleagues, Captains
Maurice Suckling and William Langdon said to have lasted just half a minute Forrest determined on attempting to carry out his orders, and bore down on the French squadron. In the
ensuing battle the British managed to disable several French ships, but were outnumbered and too badly damaged to press an attack, and after two hours of fighting, each side drew off and returned to their respective ports. The French returned to the Cape, where they refitted and then proceeded on their voyage, while Forrest went back to Jamaica. where, by the death of Rear-Admiral
Charles Holmes in November 1761, he was left senior officer. On this he moved into , hoisted a
broad pennant, and took on himself both the duties and privileges of commander-in-chief, until
Sir James Douglas, coming from the Leeward Islands in April 1762, summarily dispossessed him. Forrest returned to England, passenger in a merchant ship, when, on reporting himself to the admiralty, he was told that his conduct in constituting himself commodore was 'most irregular and unjustifiable;’ and that the officers whom he had promoted would not be confirmed. This led to a long correspondence, in which the admiralty so far yielded as to order him to be reimbursed for the expenses he had incurred, though without sanctioning the higher rate of pay. ==Slave owner==