In 1779, he joined the fleet of Count d'Estaing in the Caribbean as commander of a squadron; they were operating to counter the Royal Navy of Britain. He contributed to the capture of Grenada that year, and took part in the three actions fought by Guichen against Admiral Rodney in the Battle of Martinique (1780). Grasse was promoted to lieutenant-general of the Navy (equivalent to vice-admiral) in March 1781, and was successful in defeating Admiral Samuel Hood and taking Tobago.