Mahomet, leaving Adrianople in the early days of April with the whole of his army, overspread and ravaged the country which had not already been swept by the vanguard of his force and arrived on the 5th of that month before the city. He encamped at about a mile and a half’s distance from the landward walls. Apparently, before the arrival of the main body of Mahomet’s army, a sortie was made by the Greeks and Italians against those who had arrived, and this was possibly led by Justiniani.[234] They met at first with success, wounded many and killed a few Turks, but when Mahomet arrived the advantage of the besiegers in numbers was so overwhelming that no further sorties were attempted. The bridges leading across the foss to the Gates were broken down; the Gates were closed and were not again opened so long as the siege lasted. The Turkish army on April 6 advanced three quarters of a mile nearer to the walls, and on the following day again approached still closer. The imperial guard extended from the height crowned by Top Capou[235] to the Adrianople Gate, and thus occupied the valley of the Lycus. This district was known as the Mesoteichion. Their camp was so near to the walls as only to be just out of range of missiles discharged by the besieged.[236] [Sidenote: Formal offer of peace.] The law of the Koran requires, or is believed to require, that before war is definitely declared there shall be a formal offer of peace, and accordingly before the siege commenced Mahomet made such a proposal. To men who knew their own weakness and the tremendous odds against them any such offer must have been tempting. He sent messengers to declare that if the city were given up to him he would consent to allow the citizens to remain; he would not deprive them of their property, their wives or their children, but take all under his protection. As the inhabitants knew well the fate of a population when conquered by a Turkish army, they might possibly have accepted the proposal, if they had had any confidence in the oath of the proposer. The answer sent was that they would consent to other conditions, but never to the surrender of the city.[237] Upon this refusal Mahomet at once made his dispositions for a regular siege. [Illustration: Map of BYZANTINE CONSTANTINOPLE. Drawn by F. R. von Hubner for and under the direction of Professor A. van Millingen. _Walker & Boutall sc._ Reproduced by kind permission of Prof. A. van Millingen from ‘Byzantine Constantinople’ (John Murray). The indications in red ink are inserted by Mr. Pears. The bridges shown on the Golden Horn are modern. The red line at its mouth indicates the Boom.] CHAPTER XI TOPOGRAPHY OF CONSTANTINOPLE; DISPOSITION OF MAHOMET’S FORCES AND CANNON; ESTIMATE OF FIGHTING MEN UNDER EMPEROR; VENETIANS AND GENOESE: DISPARITY IN NUMBERS: ARMS AND EQUIPMENT: ATTACKS ON THERAPIA AND PRINKIPO. [Sidenote: Topography of Constantinople.]