While these events were going on at home, Venice was keenly interested in Eastern affairs. Now that Constantinople [Sidenote: Venice and the Turks.] had fallen, it was no longer possible to pursue the old policy of bolstering up the Eastern Empire as a buffer between the Turks and Venetian possessions. Two alternative courses were open to the republic. She might take the place of Constantinople and become the bulwark of Christendom against the infidel. Or she might endeavour to secure the continuance of Venetian commerce in the east by making an advantageous treaty with the conquerors. The heroic policy was advocated by Foscari, the more cautious and selfish policy by his opponents, and the declining credit of the doge enabled them to carry the day. In April 1454 a treaty was concluded with Mohammed II. On payment of a yearly tribute, the Venetians were allowed to retain their ports and other possessions in the east, and to continue their Levant trade in temporary security. A district in Constantinople was assigned for the residence of Venetian merchants under a Venetian bailiff. It was no small argument in favour of this treaty that it enabled Venice to strike another blow at her old rival Genoa. The Genoese had for some time aided the Turks in various ways, and had received the promise of special trade privileges as their reward. But the Sultan found it cheaper to buy off the hostility of a possible foe than to pay the stipulated price for services already rendered. For a few years Venice profited by the treaty of 1454, and abstained from giving aid to the struggling Christian populations, either of the Balkan provinces or of Greece. But the Turkish conquests were too extensive and rapid not to awaken serious misgivings. In spite of the famous relief of Belgrad by Hunyadi, Servia was reduced, and Wallachia and Bosnia were overrun without serious resistance. Only Albania, under the heroic Scanderbeg, succeeded by desperate efforts in prolonging its independence, and in extorting terms from the Sultan. It was more alarming to the Venetians when the Turkish armies crossed the isthmus into the Morea, and equipped a fleet for the conquest of Lesbos and the other islands in the Ægean. The most strenuous opponents of war had to admit the uselessness of a paper treaty to restrain a conqueror so unscrupulous as Mohammed II. At this juncture, Pope Pius II. was making strenuous efforts to rouse the princes of Western Europe to a crusade against the Turks. Venice was convinced that the further maintenance of peace was impossible; and if the pope could secure them allies in the name of religion, their prospects of success would be improved. But these hopes of assistance were doomed to disappointment, when, in 1464, Pius proceeded to Ancona to welcome and bless the crusading host. The Venetian fleet was the only efficient force which Christendom had furnished in response to the demand of its ecclesiastical chief.