Catholic Church and the See of Rome, for the overthrow of which he had laboured so energetically, emerged triumphant from the terrible trial that had been permitted by God only for its purification. During the period that intervened between the /Ratisbon Interim/ and the death of Luther (1541-6) Charles V., hard pressed by the war with France and the unsuccessful expeditions against the Barbary pirates, was obliged to yield to the increasing demands of the Protestant princes; nor could Paul III., however much he desired it, realise his intention of convoking a General Council. But at last the Peace of Crepy (1544) which put an end to the war with France, and the convocation of a General Council to meet at Trent in March 1545, strengthened the hands of the Emperor, and enabled him to deal effectively with the religious revolution. The Protestant princes announced their determination to take no part in a Council convoked and presided over by the Pope. Charles left no stone unturned to induce them to adopt a more conciliatory attitude, but all his efforts having proved unavailing, he let it be known publicly that he would not allow himself to be intimidated by threats of violence, and that if need be he would insist on obedience at the point of the sword. John Frederick of Saxony and Philip of Hesse, alarmed by the threatening aspect of affairs, determined to anticipate the Emperor, and took the field at the head of an army of forty thousand men (1546). Charles V., relying upon the aid of the Pope and the co-operation of the Catholic princes, issued a proclamation calling upon all loyal subjects to treat them as rebels and outlaws. Maurice of Saxony deserted his co-religionists on promise of succeeding to the Electorship, joined the standard of Charles V., and in conjunction with Ferdinand directed his forces against Saxony. The Elector was defeated and captured at Muhlberg (April 1547). He was condemned to death as a traitor, but he was reprieved and detained as a prisoner in the suite of the Emperor, while his nephew, Maurice of Saxony, succeeded to his dominions. Philip of Hesse, too, was obliged to surrender, and Charles V. found himself everywhere victorious. He insisted on the restoration of the Bishop of Naumburg and of Henry of Brunswick to his kingdom as well as on the resignation of Hermann Prince von Wied, Archbishop of Cologne. He was unwilling, however, to proceed to extremes with the Protestant princes, well knowing that he could not rely on some of his own supporters. Besides, he had become involved in serious difficulties with Pope Paul III., who complained, and not without reason, of the demands made upon him by the Emperor, and of the concessions that the Emperor was willing to make to the Lutherans.