In 1754 he was a member of the chambre royale which sat during an exile of the parlement; in 1755 and 1756 he accompanied Gournay, then intendant of commerce, in his tours of inspection in the provinces, and in 1760, while travelling in the east of France and Switzerland, visited Voltaire, who became one of his chief friends and supporters.
The royal party included, beside the king and queen, their daughter Marie Therese Charlotte (Madame Royale), the king's sister Madame Elisabeth, the valet Clery and others.
Upon the disgrace of Vauban, whose Dime royale had much in common with Boisguilbert's plan, Boisguilbert violently attacked the controller in a pamphlet, Supplement au detail de la France.
Vauban's Dime royale was formerly wrongly attributed to him.
They remained in a Tirolese prison until December 1795, when there was an exchange of prisoners on the release of Madame Royale, daughter of Louis XVI., from the Temple.
