But as they were fired on by the bombard of boulevard I,[47] they did not advance along the ascent, but took shelter behind the cavalier of the left bank. The Sire de Montcler conjectured, however, that the French were preparing a real or feigned attack on this side. During the night, thirty-six feet of the northern curtain, near the tower, G, fell into the ditch, reaching from _a_ to _b_; the miners had been working for two days to accomplish this. On the morning of the 26th of September, the besiegers opened fire against the retrenchment. The dominant position of the tower, G, gave them a great advantage; and though the garrison did their best to reply, the culverins, C and D, were dismounted and the gabions thrown down about noon, when orders were given for the assault. A strong column of infantry advanced through the breach, _a b_, cutlasses in hand, and in fine order. But from the platform of the tower, F, which had remained in the power of the Burgundians, two culverins fired simultaneously on this column. Messire Charles d'Amboise supposed that the pieces in this tower had been silenced, and so they had been. But during the night, the Sire de Montcler had hoisted up three of the small pieces of the lower battery through the vault holes, and had masked them under the rubbish of the parapets. This discharge produced disorder in the column of the assailants. Fortunately for them, the pieces of the outer boulevard, in the power of the French, began to fire in their turn on the platform of the tower, P, and soon silenced the Burgundian spiroles. The assault was vigorous, well directed and well sustained, while from without the French did not cease firing on the gate and tower F, so that those of the garrison who had remained in the upper works of the gate had to abandon them and escape by the curtain and tower F.