But both proved to be impossible, even with the aid of a new instrument of war, a huge tower, the outcome of great toil and expense, which, full of troops, was wheeled against one of the gateways. This proved a failure before the showers of Turkish arrows, and was burnt to ashes as it stood. Three months of fruitless effort passed, and the host of the Crusaders began to suffer from lack of food. They dared not venture far to look for it, for the Turks were always on the watch, and no man could with safety leave his post. Finding, moreover, that the Crusaders generally got the worst of it when the Turks made a sally from the city, the native Christians of the country transferred the provisions they had been wont to bring to the former, to those from whom they now believed they would reap the greater advantage in the near future. Then hope began to fail the besiegers, whose camp, owing to the heavy rain, had now become a fever-haunted swamp. One or two of the meaner-spirited leaders {87} tried to get quietly away with their troops; even Peter the Hermit lost heart, and would have deserted the host had he not been forcibly turned back by Tancred. Meantime the Seljukian Turks had been expelled by the Saracens from Jerusalem and Tyre, and the Caliph of the latter now sent envoys to the leaders of the Crusade, of whose evil condition he had been informed, to express his surprise that the Christians, while rightly warring against the fierce Seljuks, should desire to attack Jerusalem also. He promised, moreover, to extend his protection for a whole month to any peaceable pilgrims who should wish to visit the Holy City, on condition that the Crusaders would acknowledge his supremacy in Syria; and he warned them that if they refused his terms his whole power would forthwith be directed against them. The Caliph's envoys expected to find the camp in sorry plight; but, to their surprise, they were entertained in lordly fashion, and found every sign of prosperity and plenty. They were sent back with an absolute refusal to relinquish the right of Christendom over the whole of Palestine, and quite in ignorance of the terrible straits in which the army really stood, in spite of its outward appearance of prosperity. It was true that when the enemy attacked them in the open, the Crusaders were more than able to hold their own; it was the hopeless inaction, the dread of disaffection in the camp, and the pangs of actual famine that were sapping the courage of the besiegers; and now the news that an immense army, led by the Sultan of Persia, was coming to the relief of the city was the last and most crushing blow.