With Frederick, especially in his later years, Hertzberg stood in very intimate personal relations and was often the king's guest at Sans-Souci. Under Frederick William II. his influential position at the court of Berlin was at first unshaken. The king at once received him with favour, as is clearly proved by Hertzberg's elevation to the rank of count in 1786; and Mirabeau would never have attacked him with such violence in his _Secret History of the Court of Berlin_, which appeared in 1788, if he had not seen in him the most powerful man after the king. In this attack Mirabeau seems to have been influenced by Hertzberg's personal enemies at the court. Hertzberg's political system remained on the whole the same under Frederick William II. as it had been under his predecessor. It was mainly characterized by a sharp opposition to the house of Habsburg and by a desire to win for Prussia the support of England, a policy supported by him in important memoirs of the years 1786 and 1787. His diplomacy was directed also against Austria's old ally, France. Hence it was chiefly owing to Hertzberg that in 1787, in spite of the king's unwillingness at first, Prussia intervened in Holland in support of the stadtholder William V. against the democratic French party (see HOLLAND: _History_). The success of this intervention, which was the practical realization of a plan very characteristic of Hertzberg, marks the culminating point in his career. But the opposition between him and the new king, which had already appeared at the time of the conclusion of the triple alliance between Holland, England and Prussia, became more marked in the following years, when Hertzberg, relying upon this alliance, and in conscious imitation of Frederick II.'s policy at the time of the first partition of Poland, sought to take advantage of the entanglement of Austria with Russia in the war with Turkey to secure for Prussia an extension of territory by diplomatic intervention. According to his plan, Prussia was to offer her mediation at the proper moment, and in the territorial readjustments that the peace would bring, was to receive Danzig and Thorn as her portion. Beyond this he aimed at preventing the restoration of the hegemony of Austria in the Empire, and secretly cherished the hope of restoring Frederick the Great's Russian alliance.