This general unexpected revival, the success of which was shown by the fervour of the people, the unwillingness of the authorities to make any further concessions, and the determination of all parties to insist on the strict observance of the /Ecclesiasticum Reservatum/ filled the Protestants with such alarm that their princes began to insist on new guarantees. The Emperor, Rudolph II. (1576-1612), though, unlike his predecessor, a good Catholic, was a most incompetent ruler, devoting most of his time to alchemy and other such studies rather than to the work of government. He endeavoured to solve the religious difficulties in Silesia and Bohemia by yielding to the Protestant demands (1609), but the interference of his brother Matthias led to new complications, and finally to Rudolph's abdication of the sovereignty of Bohemia (1611). Frederick IV. of the Palatinate was a strong Protestant, and was closely connected with the reforming party in England, Holland, and France. He thought he saw in the strife between the members of the House of Habsburg an opportunity of improving the position of Protestantism in the empire, of weakening the claims of the House of Habsburg to the imperial dignity, and possibly also of establishing himself as ruler of a united Germany. An incident that took place at Donauworth,[3] a city near the Rhine, helped him to realise his scheme of a great Protestant federation. This city was almost exclusively Catholic in 1555, but in one way or another the Protestants had succeeded in improving their position till at last only the abbey church remained to the Catholics. Here on the Feast of Corpus Christi in the year 1606 the customary procession of the Blessed Sacrament was attacked and dispersed, and the Catholics were treated with the greatest cruelty. When the matter was brought before the Emperor the city was placed under the ban of the empire, and Maximilian I. of Bavaria was entrusted with the task of carrying out the decree. He advanced with a strong army and captured the city. As the war indemnity could not be raised he retained possession of it, restoring to the Catholics everything they had lost. Frederick IV. made a strong appeal to the Protestant princes to show their resentment at such an act of aggression, pointing out to them that the fate of Donauworth would be the fate of all their territories unless they took united action. As a consequence when both parties met at the Diet of Regensburg (1608) the excitement was intense, and when the Emperor appealed to his princes for support against the Turks, the Protestants refused to lend their aid unless they received satisfactory explanations. The Catholics, encouraged by Maximilian, were equally unconciliatory, with the result that the Diet disbanded without having been able to arrive at an agreement.