Saint-Antonin was promoted to Lieutenant on 15 January 1762, and to Captain on 4 April 1777. He was first officer on the 64-gun "Provence". He took part in the Battle of Grenada on 6 July 1779, and took over command of "Provence" when her captain, Champorcin, was killed. He was then given command of the 64-gun "Fantasque", which he captained at the Siege of Savannah.