In a few brief words Tom explained—told how Buck Granger first had been awakened, then how all of them had heard the moans, and of the discovery of the secret switch, and then of the cavern and the bodies within. As Tom spoke the surgeon cast a queer look at him, but an instant later he was working over the unconscious Frenchman, a hand on his pulse, his ear to his heart. “Weak,” he announced at last, “mighty weak. If he survives it will be because you men reached him not a moment too soon. But at that he may be a hopeless lunatic. We can’t tell about that yet—especially when a man has gone through what this one evidently has.” The surgeon again looked down at his patient. “Why,” he ejaculated suddenly, “he wears a major’s uniform—infantry, too.” It was true. The ghastly ruin of a man that lay before them once had been a battalion commander in the French army. “Discovered at last,” the surgeon murmured, more to himself than the others. “What?” demanded Tom, quickly. “The terrible torture prison that we all have heard about, but never knew how to locate.” The surgeon paused for an instant as the unconscious man made a feeble movement. “Unquestionably,” he continued, “this is the Hun chamber of horrors known throughout the Allied armies—the Death Dungeon.” ------------------------------------------------------------------------ CHAPTER XVII JOHN BIG BEAR AVENGES IT was breaking daylight, the rain had ceased and the sky was clearing when stretcher-bearers arrived to remove the unfortunate Frenchman from the squalid shed which had been the roof of his dungeon prison. A steady and terrific pounding of the big guns in the rear had begun. And as though the first shot had been the signal for general activity, the vast area occupied by the American troops became suddenly peopled with thousands of khaki-clad men. They swarmed here, there and everywhere, apparently springing to life and action from nowhere. The individuals formed into small groups, and these in turn rapidly mingled with and became parts of larger units; and thus uninterruptedly the process continued until, in the briefest conceivable time and with remarkable system and precision, and even before the sun was well above the horizon, an army had been reassembled and was ready to follow the creeping barrage which would be laid down by hidden artillery, as soon as its present firing had mowed away wire entanglements and other obstructions which aerial observers already had reported the Germans as having left behind them as they began another day’s retreat.