It was through streets strewn with the red work that the Austrian envoy, on the verge of desperation, made his way to the house of Vaulgrenant,[358] whom he found but moderately willing to listen to proposals in doubtful favour with the ministry at home, and to the prejudice of the man who might sleep that night in the capital of his fallen enemy. The conference was without result; it was never resumed.[359] Through the combined efforts of d'Argenson and Frederick the whole negotiation had come to nothing; and Maria Theresa had no alternative but to sign with Frederick the Treaty of Dresden. By this treaty the Convention of Hanover was confirmed. Frederick was free to withdraw from the war, and he was again recognised as sovereign of Silesia. This was the last great blow which French policy sustained during the year 1745. Frederick had broken finally with France. Months before, when the position had first been suggested by the news of the Treaty of Hanover, d'Argenson had conceived his policy in regard to it. He knew better than any man the real causes of Frederick's defection; and deplore it as he might, he saw no reason for enlisting Prussia among the enemies of France. He had expressed his thought in a letter to Belleisle:--[360] "We must leave him alone; he will remain neutral; he will deceive the Queen of Hungary as he deceives everybody else; he will continue to cause her uneasiness until the general peace, and it is his interest to do so; he will oblige her always to keep an army in the neighbourhood of Silesia.... We can retain his alliance by interest, or at least by a certain understanding which prevents him hurting us, and which will be useful to us in many ways." "In fact, as he told the Prussian ambassador as soon as the Treaty of Dresden was known, he regarded Prussia as henceforth the political centre of French interests in the Empire and in the north."[361] So concludes this study of the position really occupied by d'Argenson with regard to the political events of 1745. It is not without reason that it has been dwelt upon at length; for the period embraced seems immeasurably the more important of d'Argenson's ministry. The principal events of the following year are really no more than episodes, loose, and comparatively of little weight. In 1745 however, we have a long and connected series of incidents, affording an extended view of the rival policies; and furthermore, we are brought directly into contact with the great political question of the day, the question suggested by the growing change in the relations of the German powers.