His parents were Jacques Ambert and Marianne Rouchon. In 1780 he shipped as a volunteer aboard the "Pluton (74)" during the American Revolutionary War. During that conflict he participated in the Battle of Martinique during the attempted recapture of Saint Lucia in 1780 and in the successful Invasion of Tobago in May and June 1781. The "Pluton" was also engaged at the Battle of the Chesapeake on 5 September 1781. Later, the ship was part of Admiral Louis-Philippe de Vaudreuil's squadron which fought at the Battle of the Saintes in April 1782. The "Pluton" survived that defeat because it called at Portsmouth, New Hampshire on 10 October 1782. Ambert returned to France in 1783.