Outside the city the prospects for successful resistance were quite as bad. When a delegation came from the East to beg their help, they were referred by the Signoria to the Holy Father, as the head of the crusading program. Yet they began to suspect something was wrong when one of their ships, coming out of the Bosphorus, was fired on by the Turks, and the crew was taken and massacred. There were a few Venetian merchants’ galleys in the harbor whose crews, at the Emperor’s request, took part in the work of defending the fortifications. The Genoese, fearful of the fate of their colony at Pera, sent an armed force of 1000 men to help defend the city. While keeping up a constant blockade, Mohammed was preparing his plans. His success, he saw, depended on siege guns, for he fully appreciated the tremendous revolution in warfare due to the use of gunpowder. From the many renegades in his camp he had heard of the remarkable effects produced by bronze cannon in battles and sieges. His adviser in preparing his siege guns was Urban, probably a Roumanian renegade, who showed great skill in perfecting the technique of projectiles at this early stage of their use. To the inventive faculty of this Christian fugitive in the Osmanli camp, the taking of the great Christian capital in the Orient was largely due. The weight of the new guns is shown by the fact that it took sixty oxen to draw the first one, which was manufactured by the end of February. Fifty similar ones were ordered to be constructed. Troops from Asia and Slavic contingents from Europe kept gathering round the city during the winter and early spring; there was besides an Ottoman flotilla of 300 vessels. By the beginning of April, 1453, the Sultan, with his court, came to the encampment of the besieging army, and took up a position two miles and a half away from the city walls. To each portion of the fortifications a certain contingent was assigned, specific directions to proceed with the attack being given, according to the character of the ground and the defenses. In the Sultan’s army there were probably as many men under arms as were usually taken in the Turkish military expeditions, between forty and sixty thousand, but the number is not given in the sources. The Emperor Constantine had not more than 7000 men; besides, as we have seen, the population were ill disposed to him, because of his concessions to the Latin Church, and more than once the hostile cry was heard within the walls, “better under the Turks than under the Latins.” One of Constantine’s chief officials, Lukas Notoras, had already exchanged his Christian headgear for a Turkish turban.