Castellane-Majastre served in the American Revolutionary War, commanding the 32-gun frigate "Flore" in 1778. He later served in the squadron under Grasse, leaving from Brest on 22 March 1781, bound for Martinique. He served in the Invasion of Tobago on 30 May 1781. The campaign led to the capture of Cornwallis. Castellane-Majastre took part in the Battle of the Chesapeake on 5 September 1781 and the Siege of Yorktown on 19 October 1781.