In 1750 he was appointed to head the stables of King Louis XV and appointed governor of the Château de Vincennes in 1754. In addition to Switzerland, he served as French ambassador to Poland, Venice and to the Holy See. He followed his uncle as war minister when the latter was forced from office by the influence of Madame de Pompadour in 1757. The outbreak of the Seven Years' War made this post exceedingly difficult to hold, and he resigned on 23 March 1758.