Before sunrise the baron commenced a countermine at the point indicated by the deserter, inside the bailey wall. "If thou mistakest by so much as a yard," said the baron to the harness-maker, "thou shalt be hanged." The work was carried on by both parties, and towards the close of the day the miners and counterminers met and attacked each other in their close quarters with crowbars and pickaxes. The Burgundians and the Lord of Roche-Pont each sent men to seize the mines. A barrel of Greek fire dislodged the duke's men; but the masonry of the wall, whose mortar had not thoroughly set, cracked above the mine. Seeing this, the Burgundians next night, making use of the rescued portion of the _cat_, set up a kind of front-work, formed of pieces of timber; and in the morning brought a _bosson_, or battering-ram on wheels (Fig. 43), with which they set to work to batter the base of the wall. At each blow the masonry was shaken, and stones fell down within and without. The besieged tried to break the _bosson_, by letting fall great pieces of timber on its head, and to set fire to the timber; but these had been wetted, covered with mud, and filled round with manure at the bottom: the parapet was so well swept by the duke's mangonels and by the crossbow men that it was scarcely possible to retain a footing on it. Besides the men upon this wall, shaken as it was and vibrating at every blow of the ram, lost their self-possession and did not do their best; while the _bosson_ held out, especially as the assailants had put large pieces of timber in an inclined position against the wall, which caused the beams thrown by the besieged to slide off. At the end of three hours of continued effort, the wall gave way, and a piece about twelve feet long fell on the bosson. The Burgundians immediately bringing up planks and ladders rushed to the assault through the narrow breach. The struggle was severe, and the garrison themselves, mounted on the ruins of the wall, fought bravely and maintained their front unbroken. From the parts of curtains that remained intact and from the towers the defenders showered darts and stones on the assaulting column. The trebuchets within the rampart continued to send stones which, passing over the heads of the defenders and assailants on the breach, struck those who were gathered around the remains of the _cat_, and made wide lanes among them. By the evening, the Burgundians were masters of the breach; but seeing the interior rampart before them they did not venture to descend, but took up a position on the breach, protected by mantelets and fascines.