There was little chance of permanent success so long as the princes and states of the West with their divergent interests, dynastic or commercial, confronted such a solidly compacted power as that raised up by Osman. The Turks had a single aim, simple and direct, and they kept hammering away at their enemies, putting in telling blows at the right moment and the right place. On the other hand, the Christian cause suffered both from the leadership of the Papacy, with its rigid insistence on establishing Western ecclesiastical rule in the East, and from the sordid self-seeking of the Genoese and Venetians. From both points of view the conquest of the Greek Empire was generally regarded as a necessary preliminary for making headway in the restoration of Christian control over the Holy Land. The hard case of the Eastern Emperor, whose few remaining possessions were in the fast-closing grip of the Ottoman Sultan, is sketched indelibly in the narrative of the Western journey of John V, who, while the Turks were absorbing the Slavic lands about his empire, visited Rome to ask the Pope’s aid. In the desperate state of his resources he had borrowed at Venice, at exorbitant rates of interest, money to pay the expenses of his trip. On his return empty-handed he was stayed at Venice by his creditors, and the republic put him in prison. His son, Andronicus, associated with his father in the Empire, had been left behind at Constantinople. When the Emperor appealed to him for aid, the reply came that the treasury was empty. The unfortunate sovereign appealed with more success to a younger son, Manuel, who mortgaged his estates and enabled his father to return home. In May, 1372, the Pope again took the initiative in organizing an anti-Ottoman league by writing to the Republic of Venice and the King of Hungary a letter which described the achievements of the “Saracens” in Thrace, their defeat of the “Servian lords in Greek lands,” and the prospects of a farther advance of the infidel towards the Adriatic. Bad news had come from Greece, too, of the possibility of the Turkish invaders penetrating towards the south. A congress of the Balkan states was called to meet at Thebes, a place under Frankish and Roman Catholic rule; and it was a significant fact that no member of the Eastern Church was asked to be present. A gathering of such a restricted character could do nothing. There were at Thebes only a few representatives of the small Latin principalities in Continental Greece and the islands. Immediately after this gathering the Byzantine clergy put forth in Constantinople a formal protest against the See of Rome and appealed for help to the Knights of Rhodes.