Yet, in the middle of their desperate struggle for national existence against German and Hungarian, the Calixtines and Taborites could not be induced to suspend their internal quarrels. Z̆iz̆ka, indeed, desired at first to adopt a more conciliatory policy than was customary with his colleagues; and he persuaded the Taborites to act with the citizens of Prague in offering the crown of Bohemia to the King of Poland. But even he soon felt compelled to adopt a more aggressive line of action; for the Calixtines had been so alarmed at the power of John of Z̆elív, that they had prohibited the further introduction of novelties in doctrine, and had deposed those Councillors of the Old Town who had been elected under the influence of John. Z̆iz̆ka was so alarmed at these proceedings, that he abandoned a siege which he was conducting in a distant part of Bohemia, and marched against the fortress of R̆íc̆an, which was in the near neighbourhood of Prague. This fortress had long been a danger to the citizens; but they were perfectly well aware that Z̆iz̆ka’s present motive for marching against it was a desire to control the deliberations of the Town Councillors. Hynek of Crus̆ina was so indignant at Z̆iz̆ka’s conduct that he threw up the captaincy of Prague, and not long after adopted the cause of Sigismund. Z̆iz̆ka had his usual good success in the siege; but there is at least a doubt whether his proceedings were marked by his usual good faith. The Calixtine leaders had promised to spare the lives of the defenders of the fortress if they would surrender; yet, after the surrender was completed, Z̆iz̆ka burnt alive nine of the priests whom he found in the garrison. But neither the undoubted cruelty nor the possible treachery of this proceeding could prevent Z̆iz̆ka’s victory from producing the desired effect on the Calixtines; and they now consented to admit the Taborites to a free discussion of the points of difference between them and their rivals. This discussion had at least one advantage. It showed clearly what was the point which the Taborites looked upon as the vital difference between themselves and the Calixtines. For, when the Masters of the Prague University brought forward a long list of subjects of controversy, one of the Taborite leaders complained that they had not come there to discuss all those points; but that they simply wished for a decision on the question whether they should or should not wear special vestments at the performance of the Mass. Jakaubek of Kladrau consented to limit the discussion to this one point; and, although no resolution was arrived at, the Taborites clearly saw that the majority in Prague were against them. The fierce spirit of fanaticism, which had already led the Taborites into such excesses, now roused them to fury against the Calixtines; and in one town, at least, they proclaimed that any priest who was found wearing a special dress at the celebration of the Mass, should be burned alive in his vestments.