We have seen that during the seven weeks in which Mahomet’s army had been encamped before the triple walls of the Queen City he had attempted to capture it by attacks directed almost exclusively against the landward walls. He was now preparing to make one directed upon all parts of the city together. Hitherto, notwithstanding his balistas, mangonels, and spingards, his turrets, his cannon and his mining operations, he had failed. But his preparations had all rendered the general assault which he contemplated more formidable in character and easier of accomplishment. He had collected together all the various appliances known to mediaeval engineers for attacking a walled city; two thousand scaling-ladders were ready for the assault, hooks for pulling down stones, destroying the walls, and forcing an entry. But the amassing of all his paraphernalia, and even all his mining operations, sink into insignificance as preparations for a general attack when compared with the work done by his great cannon. Primitive as they were in construction when measured with the guns of our own days, the Turks had employed them effectively. [Sidenote: Breaches made by Turks in three places.] They had concentrated their fire mainly in three places. Five cannon had discharged their balls against the walls between the Palace of Porphyrogenitus and the Adrianople Gate; four, among which was the largest, against those in the Lycus valley near the Romanus Gate, and three against the walls near the Third Military Gate. [Sidenote: Lycus valley chief point of attack.]