Distinguished himself in Hanover during the Seven Years War. Maréchal de camp (1770). Succeeded his father as Governor of Boulonnois (1770).
Asked Franklin to send him the latest findings on lightning rods, which he planned to install on his residences in Picardy and Paris.
Married to Félicité-Louise Le Tellier de Courtanvaux, daughter of the marquis de Courtanvaux, Franklin’s colleague at the Académie des Sciences (1759).