Pope Gregory XII

The two claimants opened wary negotiations to meet on neutral turf at Savona in Liguria, but soon began to waver in their resolve. The Corraro relatives of Gregory XII in Venice and King Ladislaus of Naples, a supporter of Gregory XII and his predecessor for political reasons, used all their influence to prevent the meeting, and each claimant of the papal title feared being captured by partisans of his rival.[4]

The cardinals of Gregory XII openly showed their dissatisfaction at this manoeuvring and gave signs of their intention to abandon him. On 4 May 1408, Gregory XII convened his cardinals at Lucca and ordered them not to leave the city under any pretext. He tried to supplement his following by creating four of his Corraro nephews cardinals – including the future Pope Eugene IV, despite his promise in the conclave that he would create no new cardinals. Seven of the cardinals secretly left Lucca and negotiated with the cardinals of Benedict XIII concerning the convocation of a general council by them, at which both Gregory XII and Benedict XIII should be declared deposed and a new pope elected. Consequently, they convoked the Council of Pisa and invited both claimants to be present. Neither Gregory XII nor Benedict XIII appeared.

Meanwhile, Gregory XII stayed in Rimini with the family of his loyal and powerful protector, the condottiero Carlo I Malatesta.[6] Malatesta went to Pisa in person during the process of the council to support Gregory XII. At the fifteenth session, 5 June 1409, the Council of Pisa declared that it deposed both Gregory and Benedict as schismatical, heretical, perjured, and scandalous; they pronounced that they had elected Alexander V (1409–10) later that month.[7] Gregory XII, who had meanwhile created ten more cardinals, had convoked a rival council at Cividale del Friuli, near Aquileia; but only a few bishops appeared. Gregory XII's cardinals pronounced Benedict XIII and Alexander V schismatics, perjurers, and devastators of the Church, but their pronouncement went unheeded. Gregory XII was very saddened by the way he was treated; he also had some adventures while barely escaping from enemies and former friends.[8]

The Council of Constance finally resolved the situation. Gregory XII appointed Carlo Malatesta and Cardinal Giovanni Dominici of Ragusa as his proxies. The cardinal then convoked the council and authorized its succeeding acts, thus preserving the formulas of papal supremacy.

Thereupon on 4 July 1415, Gregory XII's resignation was pronounced in his name by Malatesta and accepted by the cardinals. As they had agreed previously, they retained all the cardinals created by Gregory XII, thus satisfying the Corraro clan, and appointed Gregory XII Bishop of Frascati, Dean of the College of Cardinals and perpetual legate at Ancona. The Council then set aside Antipope John XXIII (1410–15), the successor of Alexander V. After the former follower of Benedict XIII appeared, the council declared him deposed, ending the Western Schism. A new Roman pontiff, Martin V, was elected after the death of Gregory XII, which many took as an indication that Gregory had been the true pope.[9] Therefore, the Papal seat was vacant for two years.