In 1751, he was made
chef d'escadre des vaisseaux du roi, then governor of Martinique. On 20 April 1752, he acquired the château de La Ferté-Avrain, which had recently been rebuilt. In recognition of his services to France, on 7 July 1764
Louis XV promoted him to the status of
marquis, allowing him to raise his lands at La Ferté-Avrain into the
marquisat. From then on, La Ferté-Avrain was called La Ferté-Beauharnais after him. ==Royal descendants==