COSSA (COSCIA), BALDASSARE, ANTIPOPE. - Of a noble Neapolitan family. Hostile legends were spread about his youth; it is certain that he was a familiar of Cardinal Pietro Tomacelli; when the latter was elected pope under the name of Boniface IX (1389), Cossa became a chamberlain, and he did not hesitate to use means to make money; and for money he managed to be created cardinal deacon of S. Eustachio on 27 February 1402. He held the government of Bologna as legate and on 26 June 1409 was among the electors of Alexander V (v.), of the obedience of Pisa.
He hastened to conduct the elector to Bologna where he died; and on 17 May 1410 in that city Cossa was elected to succeed him under the name of John XXIII. Having succeeded in making peace with King Ladislaus of Naples, he was able to convene a council in Rome during 1413, as had been decided at Pisa in 1410, and there condemned the writings of Wycliffe. But forced to leave the city, he took refuge in northern Italy, and at the insistence of Sigismund, King of Germany, he convoked the Council of Constance for 10 November 1414. He was indeed present on the appointed day, hoping to prevail over his two adversaries: Gregory XII,
the legitimate pope, and Benedict XIII, the pope of Avignon. Realizing that ill repute was circulating against him at Constance, taking advantage of a solemn tournament he secretly left the city on 20 March 1415 with the covert favour of Frederick, Duke of Tyrol. He hoped that the Council would be dissolved; but King Sigismund, who was present, managed to have it continue in order to provide for the end of the schism and the reform of the Church. The Council indeed asserted its authority and in May cited John to appear. He, who from Schaffhausen, where he had taken refuge, had gone to Laufenburg, then to Freiburg and Breisach, abandoned by the Duke of Tyrol, submitted, was imprisoned at Radolfzell; and on 29 May he was deposed, after a brief trial, “as a simoniac, a squanderer of ecclesiastical goods, an unfaithful administrator of the Church both in spiritual and temporal matters.” In that same council which he had convened, John ratified this sentence without offering any opposition. He remained a prisoner under strict custody and the surveillance of Louis of Bavaria in the castle of Hausen. He then recognized in 1415 as the true pope Martin V; the latter in turn appointed him cardinal bishop of Tusculum (1419). Cossa died in Florence on 22 November 1419 and was buried in the city’s baptistery, where a funerary monument was erected to him by order of Cosimo de’ Medici by Michelozzo and Donatello.