Louis, constantly occupied by his expedition, fixed the period of his departure for 1270; so that three long years must pass away before the assistance promised by the sovereign pontiff could arrive in the East. Vessels to transport the Crusaders were demanded of the republics of Genoa and Venice: the Venetians at first refused; but upon learning that applications were being made to the Genoese, they sent ambassadors to offer a fleet. After protracted negotiations, in which Venice evinced more jealousy of the Genoese than zeal for the crusade, she again refused to concur in the embarkation of the Christian army, being in less dread of the anger of Louis IX. than of that of the sultan of Cairo, who had it in his power to ruin her mercantile establishments in the East. At length the Genoese engaged to furnish vessels for the expedition. But the greatest difficulty was to find the money necessary for the preparations of the war. Up to this period, the tenths levied upon the clergy had supplied the expenses of the crusades;[23] and an opinion generally prevailed, that a holy war ought to be paid for by men attached to the Church and devoted to the altars of Jesus Christ. Urban IV., the predecessor of Clement, had already ordered throughout the West, that a levy of a hundredth should be made upon the revenues of the clergy; and, what might be considered a traffic in holy things, the court of Rome permitted the distributing of indulgences, which faculty was granted in proportion with what was given beyond the tribute required. The French clergy had addressed several petitions to the pope upon this subject; but these petitions always remained unnoticed.