In 1778, Chabert captained the 64-gun "Vaillant" in the squadron of D'Estaing. He took part in the Battle of St. Lucia on 15 December 1778, and in the Battle of Grenada on 6 July 1779. On 28 August 1779, D'Estaing's squadron arrived at Boston, and Chabert installed mortars on Gallops Island for the defence of Boston harbour. In October, Chabert took part in the Siege of Savannah.