Isaac Pasha, the head of the Asiatic troops, and Mahmoud, both men who had had great experience in war, commanded the Asiatic division, which covered the ground between Top Capou and the Marmora.
The most important position, however, was that which existed between the Adrianople Gate and Top Capou known as the Mesoteichion. This was the place which Mahomet chose as the principal point of attack. There, he considered, was the Achilles’ heel of the city. There, with Halil Pasha under him, were his head-quarters. His lofty tent of red and gold[252] was pitched about a quarter of a mile from the walls on a small knoll, which is described as opposite the Adrianople Gate and also as opposite that of Romanus. His tent was surrounded by those of the invincible Janissaries who, with other chosen troops, constituted his bodyguard and occupied the same valley.
The Turkish army extended in front of the entire length of the landward walls. The Turks had dug a trench for their own defence in front of the whole of their line, and had placed a wooden palisade upon the earth thus dug out. This was quite near the edge of the foss itself and was pierced at intervals, so that, while it protected the besiegers, it also allowed them to keep up a constant fire on the besieged.[253]
On the Marmora the walls were to be watched by the fleet under Baltoglu from the southern end of the landward walls, round the present Seraglio Point as far as Neorion, which was near the end of the boom. The main object of the fleet was, however, to force an entry into the harbour, and for this purpose to capture or destroy the ships at the boom, an object which Baltoglu attempted to attain from the very commencement of the siege.[254]
The city was thus under attack on two sides, the third—namely, that looking over the Golden Horn—protected by the boom, was for the present inaccessible to the Turkish fleet.
The difficulty of determining the number and disposition of Mahomet’s cannon opposite the landward walls arises from the fact that the position of several of them was changed and that their numbers possibly varied. Phrantzes mentions fourteen batteries along the length of the wall, each containing four guns. Barbaro speaks of nine batteries. Montaldo says that the Turks had in all two hundred guns or ‘torments.’[255] Each of the nine batteries was strengthened by the addition of a heavy gun. Critobulus represents Mahomet as stating after his guns had done their work that he had opened a way into the city at three places, and this declaration affords a safe guide to the general disposition of the cannon. These were, first, between the present Tekfour Serai and the Adrianople Gate; second, opposite or near the Pempton or Gate of the Assault (usually spoken of by contemporaries as the Romanus Gate[256]) in the Lycus valley, and the last near the Third Military Gate between the Pegè or Silivria Gate, and the Rhegium Gate, now called Mevlevihana Capou. Here were the three principal stations of Mahomet’s cannon. At these three places the ruined condition of the wall bears testimony to the vigorous attack of cannon. At them and nowhere else is it possible to pass over the foss, the breastwork and Outer Wall, and to see that the Inner Wall has been so broken down that a passage into the city was possible.[257]
Three cannon are especially remembered on account of their great size. According to Leonard, the largest—that, namely, cast by Urban, which threw a ball of twelve hundred pounds weight—was first placed at Caligaria[258] which then, as now, was ‘protected neither by a foss nor by a front wall.’ It was destroyed either by the besieged or through an accident by which Urban was killed, after it had done considerable damage to the walls.[259] It was, however, recast and transferred to the Lycus valley, where it demolished the Bactatinean tower.[260] The statement of Chalcondylas is that of these three large guns one was stationed opposite the Imperial Palace, probably at Caligaria, the second opposite the Romanus Gate, where the sultan had fixed his camp, and the third between them.[261]
The largest and most powerful gun remained during the siege at the Mesoteichion, in front of the imperial tent.[262]
These cannon are variously described as bombards, machines, skeves, helepoles (or ‘takers of cities’), torments, heleboles, and teleboles. They threw stone balls of great size. The balls had been brought from the Black Sea. The largest, says Chalcondylas, was fired seven times a day and once each night. Archbishop Leonard states that he measured one which had been fired over the wall, and found it to be eleven spans (or eighty-eight inches) in circumference. Nor is such measurement exaggerated. Some of the stone balls have been preserved. They were probably fired over the wall, did not break, and remain nearly in the position where they fell. I have measured two of them, and they are exactly eighty-eight inches in circumference.[263] Tetaldi states that there were ten thousand culverins, and the same number is given by Montaldo. The number is possibly exaggerated. Yet Leonard speaks of ‘innumerable machines’ being advanced towards the wall, and afterwards of a great number of small guns being employed to batter the walls along all their lines. None of the cannon, I think, were mounted on wheels: the Great Cannon certainly was not, for Critobulus describes how it was first carefully pointed towards the object intended to be struck, and then embedded in its position with blocks of wood preparatory to firing.