John, name of 22 popes and 2 antipopes. Saint John I (d.526), pope (523–26), was sent to Constantinople by Theodoric, the Ostrogoth king, to win toleration for Arianism from the emperor; Theodoric imprisoned him when he failed. John VII (d.882), who reigned from 872 to 882, sought political power for the papacy. He attempted (and failed) to keep the Muslims out of Italy and was forced to pay tribute in order to spare Rome. He momentarily resolved a dispute with the Eastern Church by recognizing Photius as patriarch of Constantinople (879), after the death of his enemy, St. Ignatius. He crowned emperor Charles II (the Bald, in 875) and Charles III (the Fat, in 881). He was assassinated by members of his household. John XXII (1249–1334) was the second pope (1316–34) at Avignon; he filled the college with French cardinals. A skillful administrator, he lost popularity when he persecuted the Franciscan Spirituals, observers of strict evangelical poverty. When he contested the election of Louis IV, the king attempted to have him declared a heretic; this prompted John to imprison Nicholas V, the antipope Louis had appointed. The name of John XXIII was first taken by Baldassare Cossa (c. 1370–1419), a Neapolitan antipope (1410–15). As a cardinal, he supported the Council of Pisa (1409), which tried (unsuccessfully) to end the Great Schism between the popes of Rome and Avignon. Elected pope by the Council, he defended Rome against his rival, Gregory XII, and, pressured by Emperor Sigismund, convened the Council of Constance to attempt reconciliation again. He agreed to abdicate if his rivals would as well, but then reneged. The Council accepted Gregory's resignation and deposed the other two. The name John XXIII was next taken by Angelo Giuseppe Roncalli (1881–1963). Of peasant stock, he was elected pope in 1958 after serving as cardinal and patriarch of Venice since 1953. He made major changes in the church, promoting cooperation with other Christian churches and other religions. The encyclical Mater et Magistra (1961) advocated social reform in underdeveloped countries. In 1962 he convened the Second Vatican Council.