The outbreak of the Seven Years' War made this post exceedingly difficult to hold, and he resigned on 23 March 1758.

[1] He was a noted bibliophile and collector of art, whose private hope, reported in his memoirs[2] was to be appointed director of the Bâtiments du Roi, a post that devolved upon Mme de Pompadour's highly competent brother.

He built a château at Asnières[3] in 1750, with expenses that scandalized his virtuous uncle, to set the tone for the Court and display his collection of works by Northern Renaissance masters.

He planned the Bibliothèque universelle des romans, published between 1775 and 1778 in 40 octavo volumes, a collection of novels including some of his own writing.

[1] His collection of publications from the German-speaking area was supplied by the Strasbourg publishing house Bauer, Treuttel and Würtz.