After fighting under d'Estaing, he was made second in command of the 74-gun "Glorieux", which became part of the comte de Grasse's squadron in March 1781, which in September 1781 defeated the British at Chesapeake. However, de Kerlessy was then also present at the squadron's defeat at the Saintes on 12 April 1782. When the British commander Rodney cut the French line, the "Glorieux" found itself fired on by six British ships of the line in rapid succession and her commander was soon killed. de Kerlessy then took over command, though the ship was now disabled. He then fought on for more than six hours, losing most of his crew killed and wounded before finally striking his flag and surrendering. He was taken prisoner but freed in 1783. His heroic defense resulted in his acquittal at the court martial for the loss of his vessel. He was promoted to capitaine de vaisseau in 1784 and given the cross of the order of Saint-Louis.