John XXIII (about 1370-1419) was an antipope during a troubled period in church history called the Great Schism (1378-1417). An antipope is a man determined to have improperly claimed to be or served as pope.
John was elected pope in 1410. At the time of his election, two other men also claimed to be pope. John had been an adventurer and accomplished soldier before his election, and he enjoyed the support of France, England, and several Italian states. Under pressure from the Holy Roman Emperor Sigismund, John agreed to call the Council of Constance (1414-1418) to resolve the rival claims to the papal throne. The council published revolutionary decrees that asserted its authority over the pope and accused John of serious crimes. He was condemned and deposed in 1415. John was born in Naples, Italy. His given and family name was Baldassare Cossa. He died on Nov. 22, 1419.
