In the early months of 1551 the friction with the Emperor on the subject of the Princess Mary's Mass was becoming alarming; Charles was refusing to let the English Ambassador in his dominions use the English Communion Service; and the Council went so far as to propose making the Princess personally and alone exempt from Conformity: fortunately, however, for them, affairs in Italy took a turn which gave fresh impulse to the anti-Imperialists in France. The Protestant city of Magdeburg was still holding out against the Imperial troops which were under the command of Maurice of Saxony, and the French King was becoming inclined to give active support to the resistance. The Pope had devoted himself to Charles's interests, and assented to the return of the Council to Trent; and there were hints that Henry might call a Gallican synod, instead of allowing the French ecclesiastics to attend, unless the Lutherans were also represented. The Emperor could no longer imagine himself to be completely master of the situation. In April, the Council felt that he was so far hampered that they could venture to assume a bold front. They informed him that the Act of Uniformity was the Law; that it applied to all subjects, including the Princess; and that they claimed the same freedom for their own ambassador which they were willing to concede reciprocally to his. About the same time the German Diet foiled a pet scheme of Charles, who wished his son Philip (afterwards Philip II. of Spain) to be nominated as his successor to the Imperial crown in place of his brother Ferdinand [Footnote: Charles had ceded the Austrian dominions of the house of Habsburg to Ferdinand in 1522.] who was already King of the Romans. The Germans however preferred the Austrian to the Spanish succession, and rejected the proposal. In June he found that the English and French had come to terms, and had agreed to a French marriage for Edward, on exceedingly easy conditions for France. He still continued to threaten war unless England gave way on the disputed points; but the Council answered only by temporising, and he was soon in no position to threaten. The unrest of the German Protestants and later in the year the assembling of the Council at Trent demanded all his attention. In fact, though he did not suspect it, Maurice of Saxony was even now laying his plans for snapping the bonds which the Emperor was seeking to rivet upon his German subjects. The incompetent hand-to-mouth conduct of foreign affairs in England did not bring disaster on the country, mainly because Charles had not rightly taken the measure of his own strength and of the forces in the Empire adverse to his policy. [Sidenote: Groups among the Reformers]