A young soldier who heard him had marked well the position of the archway, ere darkness hid it, and, maddened at the fall of his officer, he hurled a hand grenade towards the opening. The effect was instantaneous and terrific. The dreadful shock was succeeded by a still more dreadful silence. When a light was struck it was seen that every German in the inner chamber had been blown to pieces. A moment's hesitation in face of the ghastly sight, then, as the light went out again, the British sprang into the inner cell to find, or rather feel, that it was splashed and smeared with blood and clogged with spongy fragments of the mutilated dead. Cell number two, by some freak of the explosive, had not been affected, and as the third chamber thus was gained, a sergeant, shouting in the darkness, gave the eager word: "Forward again! we'll have the Fort! By God, we'll have the Fort!" Again the men pressed forward, but this time no defenders barred the way. In the distance there was a sound of hurrying footsteps. The Germans had retreated down the stone stair which led to the steel door of communication. Reinforcements had now reached the gallery, and fresh lights were brought. Well might the newcomers shudder and turn sick at what those lights revealed in chamber number three. At the moment it was quite impossible to carry the dead and wounded to the rear. Officers and men were swarming in, and none could leave the gallery. But word was passed along for surgeons to be sent, and the wounded were laid against the walls, leaving a clear gangway. Then the advance was cautiously continued. Another officer--Carlow, who had just obtained his company--now took command. Promptly but slowly, he headed the advance, for this silence, this sudden cessation of resistance, might betoken some deadly ambuscade. The men went forward, two and two. Chambers four and five proved to be quite deserted. They reached the farther archway of cell number five, and there Carlow, halting, peered down into the darkness of the narrow stair. As he stood, gazing, listening, strange and pungent fumes crept up between the walls. He gasped for breath and staggered back. The men behind him did the same. The fumes were rising, spreading--permeating the low gallery with extraordinary rapidity, travelling swiftly into every chamber. Only a few understood how this awful sense of suffocation was occasioned; and some who guessed that from an air-pump down below the Germans were pumping asphyxiating gas into the gallery guessed it too late. A few, before the gas had wholly overpowered them, fought their way back to the open, but more than a hundred men dropped where they stood in the close chambers--dropped and died. CHAPTER XVI. SIGNS AND WONDERS.