As soon as the battery was completed, gangs of men, accustomed to mining operations, set to work in its rear to drive sloping passages downwards, opening into the face of the great cutting, and through these vast quantities of earth and stones were poured, so as to afford a passage across it, the depth being largely diminished by the great pile of rubbish that had already fallen from the breached wall. This novel mode of attack was altogether unexpected. The knights had regarded the fosse that had been cut at such an enormous expenditure of labour as forming an altogether impassable obstruction, and were dismayed at seeing the progress made in filling it up. D'Aubusson himself, full of resources as he was, saw that the defence was seriously threatened, unless some plan of meeting this unexpected danger could be devised.