searching for assistance against the Ottomans. The Ottomans, who had been allied with the Kantakouzenoi, continued to press John. Suleyman Paşa, the son of the Ottoman sultan, led their forces in Europe and was able to take Adrianople and Philippopolis and to exact tribute from the emperor. John V appealed to the West for help, proposing to Pope Urban V in 1367 to end the schism between the Byzantine and Latin churches by submitting the patriarchate to the supremacy of Rome. In October 1369, John, having travelled through Naples to Rome, formally converted to Catholicism in St Peter's Basilica and recognized the pope as supreme head of the Church.<ref>"...in the presence of four cardinals, he acknowledged, as a true Catholic, the supremacy of the pope, and the double procession of the Holy Ghost. After this purification, he was introduced to a public audience in the church of St. Peter: Urban, in the midst of the cardinals, was seated on his throne; the Greek monarch, after three genuflections, devoutly kissed the feet, the hands, and at length the mouth, of the holy father, who celebrated high mass in his presence, allowed him to lead the bridle of his mule, and treated him with a sumptuous banquet in the Vatican." – Edward Gibbon, The History of the Decline and Fall of the Roman Empire, Chapter 66 (Visit of John Palaeologus to Urban V. at Rome, A.D. 1369, 13 October etc.), via the Christian Classics Ethereal Library</ref> He was not accompanied by the clergy of the Byzantine Church and the move failed to bring about an end to the Schism. Impoverished by war, he was detained as a debtor when he visited Venice in 1369 on his way back from Rome and was later captured on his way back through Bulgarian territories. In 1371, he recognized the suzerainty of the Ottoman sultan Murad I. Murad later assisted him against his son Andronikos when the latter deposed him in 1376. Deposition and second rule In 1390, his grandson John VII briefly usurped the throne, but was quickly overthrown. The same year, John V ordered the strengthening of the Golden Gate in Constantinople, utilizing marble from the decayed churches in and around the city. Upon completion of this construction, Bayezid I demanded that John raze these new works, threatening war and the blinding of his son Manuel, whom he held in captivity. John V carried