COSSA (COSCIA), BALDASSARE, ANTIPOPE. — Of a noble Neapolitan family. Hostile legends spread concerning 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), C. became a cubicularius and had no scruple about using every means to make money; and through money he succeeded in having himself created cardinal deacon of S. Eustachio on 27 February 1402. He governed Bologna as legate and on 26 June 1409 was among the electors of Alexander V (v.), of the Pisan obedience.
He took care to conduct the elected pope to Bologna, where the latter died; and on 17 May 1410, in that city, C. was elected to succeed him under the name of John XXIII. Having succeeded in making peace with Ladislaus, king of Naples, he was able during 1413 to convene a council at Rome, as had been established at Pisa in 1410, and there condemned the books of Wiclef. But compelled to leave the city, he took refuge in northern Italy and, at the urging of Sigismund, king of Germany, announced on 3 October the Council of Constance for 1 November 1414. He was indeed present there 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 reports about him were circulating at Constance, he took advantage of a solemn tournament to leave the city secretly on 20 March 1415, with the covert support of Frederick, duke of Tyrol. He hoped that the Council would be dissolved; but King Sigismund, who was present, succeeded in having it continue in order to bring about the end of the schism and the reform of the Church. The Council in fact affirmed its own authority and in May summoned John to appear. Having fled from Scifusa, where he had taken refuge, to Laufenburg, then to Freiburg and Breisach, and abandoned by the duke of Tyrol, he submitted and was imprisoned at Radolfzell; on 29 May he was deposed, after a brief trial, “as a simoniac, dissipator of ecclesiastical goods, and 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 under the supervision of Louis of Bavaria in the castle of Hausen. He subsequently recognized Martin V as the true pope in 1418; the latter in turn appointed him cardinal bishop of Tusculum (1419). C. died in Florence on 22 November 1419 and was buried in the city’s baptistery, where a funerary monument was erected for him by order of Cosimo de’ Medici, by Michelozzo and Donatello.