Of the clerical members of the council the most prominent at the commencement was the pope John XXIII. He had been forced by his difficulties in Italy to issue the summons, but as the time for the meeting approached he felt more and more misgiving. His object was to maintain himself in office; but he was conscious that neither Sigismund nor the cardinals would hesitate to throw him over if he stood in the way of the restoration of unity. He therefore allied himself with Sigismund's opponents, the Elector of Mainz and Frederick of Tyrol, and spared no pains to bring about dissension between Sigismund and the council.
The assembled clergy may be divided roughly into two parties, the reformers, and the conservative or ultramontane party. The reformers were not in favor of any radical change in the Church. They were, if anything, more vehemently opposed than their antagonists to the doctrines of Wycliffe and Huss. Such reform as they desired was aristocratic rather than democratic. They had no intention of weakening the authority of the Church; but within the Church they desired to remove gross abuses, and to strengthen the hierarchy as against the papacy. Their chief contention was that a general council has supreme authority, even over the pope, and they wished such councils to meet at regular intervals. By this means papal absolutism would be limited by a sort of oligarchical parliament within the Church. The conservatives, on the other hand, consisting chiefly of the cardinals and Italian prelates, had no wish to alter a system under which they enjoyed material advantages. Their object, as it had been at Pisa, was to restore the union of the Church, but to defeat, or at any rate postpone, any schemes of reform.
The council was opened on November 5th, but the meeting was only formal, and no real business was transacted for a month. Meanwhile Huss had been followed to Constance by the representatives of the-orthodox party in Bohemia, who brought a formidable list of charges against the reformer. John XXIII at once saw in this an opportunity for embroiling the council with Sigismund. Adroitly keeping himself in the background, he allowed the cardinals to take the lead in the matter. They summoned Huss to appear before them, and in spite of his protest that he was only answerable to the whole council, they committed him to prison. The news that his safe-conduct had been so insultingly disregarded reached Sigismund as he was starting for Constance after the coronation ceremony at Aachen.
He arrived on Christmas Day, and at once demanded that Huss should be released. The Pope excused himself, and threw the blame on the cardinals. To the King's right to protect his subject the cardinals opposed their duty to suppress heresy. In high dudgeon, Sigismund declared that he would leave the council to its fate, and actually set out on his return journey. The Pope was jubilant at the success of his wiles. But Sigismund's friends, and especially Frederick of Hohenzollern, urged him not to sacrifice the interests of Germany and of Christendom for the sake of a heretic. This advice, and the feeling that his personal reputation was staked on the success of the council, triumphed. Sigismund returned to Constance, and Huss remained a prisoner. From this moment John XXIII began to despair.
The Pope's position became worse when the council, copying the procedure of the universities, began to discuss matters, not in a general assembly, but each nation separately. This deprived John of the advantage which he hoped to gain from the numerical majority of Italian prelates attending the council. Four nations organized themselves: Italians, French, Germans, and English. Over the last three John XXIII had no hold whatever. To his disgust they treated him, not as the legitimate pope, whose authority was to be vindicated against his rivals, but as one of three schismatic popes, whose retirement was a necessary condition of the restoration of unity. When he tried to evade their demand, they brought unanswerable charges against his personal character and threatened to depose him.
He tried to disarm hostility by declaring his readiness to resign if the other popes would do the same. His promise was welcomed with enthusiasm, but neither Sigismund nor his supporters were softened by it. In spite of the vehement protests of the Elector of Mainz that he would obey no pope but John XXIII, the proposal was made to proceed to a new election. John had to fall back upon his last expedient. If he departed from Constance he might throw the council into fatal confusion; at the worst he could maintain himself as an antipope, as Gregory and Benedict had done against the Council of Pisa. His ally Frederick of Tyrol was prepared to assist him. Frederick arranged a tournament outside the walls; and while this absorbed public interest, the Pope escaped from Constance in the disguise of a groom, and made his way to Schaffhausen, a strong castle of the Hapsburg Count.
For the moment John XXIII seemed not unlikely to gain his end. Constance was thrown into confusion by the news of his flight. The mob rushed to pillage the papal residence. The Italian and Austrian prelates prepared to leave the city, and the council was on the verge of dissolution. But Sigismund's zeal and energy succeeded in averting such a disaster. He restored order in the city, persuaded the prelates to remain, and took prompt measures to punish his rebellious vassal. An armed force under Frederick of Hohenzollern succeeded in capturing not only John XXIII, but also Frederick of Tyrol. The latter was compelled to undergo public humiliation, and to hand over his territories to his suzerain on condition that his life should be spared. No such exercise of imperial power had been witnessed in Germany since the days of the Hohenstaufen, and Sigismund chose this auspicious moment to secure a powerful supporter within the electoral college by handing over the electorate of Brandenburg to Frederick of Nuremberg, April 30, 1415. He thus established a dynasty which was destined to play a great part in German history, and ultimately to create a new German empire.
The unsuccessful flight of John XXIII not only enabled Sigismund to assume a more authoritative position in the council and in Germany; it also sealed his own fate. The council had no longer any hesitation in proceeding to the formal deposition of the Pope May 29, 1415. As the two popes who had been deposed at Pisa had never been recognized at Constance, the Church was now without a head. But instead of hastening to fill the vacancy, the council turned aside to the suppression of heresy and the trial of Huss. On three occasions, the 5th, 7th, and 8th of June, Huss was heard before a general session. No point in his teaching excited greater animadversion than his contention that a priest, whether pope or prelate, forfeited his office by the commission of mortal sin. With great cunning his accusers drew him on to extend this doctrine to temporal princes. This was enough to complete the alienation of Sigismund, and after the third day's trial he was the first to pronounce in favor of condemnation. The last obstacle in the way of the prosecution was thus removed, and Huss was burned in a meadow outside the city walls on July 6, 1415.
With the death of Huss ends the first and most eventful period of the Council of Constance. Within these seven or eight months Sigismund and the reforming party, thanks to the division of the council into nations, seemed to have gained a signal success. Sigismund had purchased his triumph by breaking his pledge to Huss, and for this he was to pay a heavy penalty in the subsequent disturbances in Bohemia. But for the moment these were not foreseen, and Sigismund was jubilantly eager to prosecute his scheme. Warned by the experience of its predecessor at Pisa, the Council of Constance was careful not to put too much trust in paper decrees. John XXIII was not only deposed, but a prisoner. Gregory XII had given a conditional promise of resignation, and had so few supporters as to be of slight importance. But Benedict XIII was still strong in the allegiance of the Spanish kingdoms, and unless they could be detached from his cause there was little prospect of ending the schism.
This task Sigismund volunteered to undertake, and he also proposed to avert the impending war between England and France, to reconcile the Burgundian and Armagnac parties in the latter country, and to negotiate peace between the King of Poland and the Teutonic Knights. It would, indeed, be a revival of the imperial idea if its representative could thus act as a general mediator in European quarrels. The council welcomed the offer with enthusiasm, and showed their loyalty to Sigismund by deciding to postpone all important questions till his return. And this decision was actually adhered to. During the sixteen months of Sigismund's absence—July 15, 1415, to January 27, 1417—only two prominent subjects were considered by the council. One was the trial of Jerome of Prague, which was a mere corollary of that of Huss, and ended in a similar sentence. The other was the thorny question raised by the proposed condemnation of the writings of Jean Petit, a Burgundian partisan who had defended the murder of the Duke of Orleans. The leader of the attack upon Jean Petit was Gerson, the learned and eloquent chancellor of the University of Paris. But so completely had the matter become a party question, and so great was the influence of the Duke of Burgundy, that the council could not be induced to go further than a general condemnation of the doctrine of lawful tyrannicide; and Gerson's activity in the matter provoked such ill-will that after the close of the council he could not venture to return to France, which was then completely under Burgundian and English domination.