 Charged with protecting the relations between the king and de Pompadour, he created a "cabinet noir" (black cabinet), in order to keep postal correspondence between their enemies under surveillance.To this cabinet has been attributed the disgrace of several enemies of madame de Pompadour, notably the comte de Maurepas and the comte d'Argenson.On the other hand, he revealed himself unable to identify the authors of heinous libels against de Pompadour.