The Papacy in the Late Middle Ages
Popes of the Schism: Rome
The first Roman pope of the Schism was Urban VI, who served from 1378 to 1389. The second Roman pope was Piero Tommasino, who took the name of Boniface IX.
Boniface IX (1389-1404)
Being of the Roman faction, Boniface naturally opposed the French generally and the Angevins specifically, since they were in southern Italy. So, he naturally championed the cause of Ladislas, recognizing him as King of Naples in 1390 (not least because Clement VII had just recognized Louis of Anjou as the king).
If it looks as though he did not accomplish much, one must remember that even to survive at this time was no small accomplishment. The Papal States were in severe disarray, and Boniface brought some measure of order there. Rome itself was so unsettled and dangerous that Boniface spent much of his time elsewhere, but he also re-fortified Castel Sant'Angelo, the papal fortress in Rome. In the north the Visconti posed a serious threat, while in the south the Angevin danger was still serious. He succeeded by holding on and holding out.
He was pope during some significant events that were Church-related. These included struggles in England over Church control, settled largely in favor of the Crown, as well as the condemnation of Wyclif. He was pope during the crusade that ended in disaster at Nicopolis. He was serving when Bianchi (a very curious religious movement that lasted only a couple of years but which much impressed contemporaries) came to Rome as part of the jubilee of 1400. In general, however, Boniface was not an activist but was mild-mannered and pious and serious. He was well-regarded and helped restore some of the damaged prestige of the Roman papacy.
Conciliarism grew as a movement during his pontificate, but Boniface absolutely refused to have anything to do with it. He held that the papal conflict could be settled by negotiation (and maneuver) between the popes, but never settled by a council, for no entity had authority greater than the pope.
Innocent VII (1404-1406)
Cosimo de' Migliorati was the son of non-noble parents who made a career for himself in the Church. He studied law at several universities and used his university connections to enter the Curia. He served in various administrative offices and was firmly in the Roman camp when he was elected pope in 1404. He was pious and learned and earnestly desired to end the Schism, but events overwhelmed him.
Almost at once there was another in the chronic disturbances in Rome. King Ladislas of Naples came to the pope's rescue, but demanded much in return, including the right to exercise a protectorate over all the Papal States. When Innocent refused, Ladislas threw his support to the insurrectionaries.
At this point (1405), Innocent's nephew waylaid some of the rebels and had them murdered. This act infuriated the Romans and Innocent had to flee the city in fear of his life. He remained at Viterbo until the following year. He did manage to return to Rome, but died soon after.
Short as it was, Innocent's pontificate is a good illustration of why the Schism went on for so long. The problem was not merely that two men each wished to be pope, nor even that there were two factions of cardinals in rivalry with one another. Also operative were various political realities, such as the people of Rome and their demands, and the Kingdom of Naples which had the only significant military force in the area. Even if other circumstances were favorable, a local disturbance or shift in powers might so preoccupy a pope that nothing at all could be done toward healing the rift in the Church.
Gregory XII (1406-1415)
When Gregory was elected, the cardinals had taken an oath that whoever was elected must promise to step down if the rival pope also resigned. A meeting of the two was arranged and both popes headed to northern Italy. There they participated in a ludicrous dance, each camp moving a little closer then backing away, for there were armed supporters near to each and both feared to be captured by the other. In the end, both popes returned home without meeting, each blaming the other.
Gregory managed to lose the support of a number of cardinals, not only for his behavior toward the Avignon pope but also because he created four new cardinalates for his relatives, despite an earlier promise not to. The disaffected cardinals met with like-minded peers from Avignon and they're the ones who created the Council of Pisa (discussed later).
Because seven cardinals had deserted him, Gregory simply created ten new ones. With these in tow, he set up his own Council in rivalry to Pisa, and with their support he refused to recognize his deposition in 1409. Gregory's intransigence, his willingness to treat the government of the Church as his personal tool for family ambitions, left him with no real support outside his Italian dependents. When the Council of Constance deposed him in 1415, he was finally forced to recognize he was powerless, and the line of schismatic Roman pontiffs came to an end.