A listening post is a branch off from the main trench toward the enemy or in his general direction, which is dug secretly as you go, the dirt being carried back in bags so as not to disclose its location. These posts must be changed often, as the enemy is apt to discover them, and then look out! Valke was standing in the darkness and seclusion of the post when a shriek rent the air, the sound of which he said he would hear through eternity. It came from a man who was prostrate on the ground. He had noticed the body lying there before, a few yards away, and had assumed that the man was dead. He was a Frenchman, and on account of the darkness could be seen with difficulty. But he was not dead, only unconscious, and something had suddenly revived him. "O God," he cried, "my marriage ring!" and then he moaned and groaned like a lost soul in agony. Immediately another form raised up to full stature and looked quickly about. Valke had to strain his eyes to see him and he trembled with nervousness. He did not know what to do for an instant. The man's head jerked this way and that. He must have expected someone to hear the cries and groans of the other man, and evidently was looking around for watchers or listeners. The Frenchman kept on groaning, and the man, seeming to fear that if any watchers were near, they would immediately let loose upon him, started to run. Valke kept very still in his dark post. Suddenly the fugitive stopped. He turned and ran back to the prostrate Frenchman. Valke saw the gleam of a knife drawn from a sheath. It was in the hand of the apache. In an instant the horrid thing was done--a swift movement of the arm, a flash, and the blade plunged into the body of the helpless soldier! Then silence: silence more terrible than the groans of agony that it stilled. Valke's fists clinched by instinct, the nails cutting into the very flesh of his palms; and then his right hand went to the holster on his hip. It was all too plain: the hideous vulture of the battlefield knew that "dead men tell no tales," and that the wounded sometimes recover and tell things that lead to fearful reprisals on their enemies. More than that: wounded men cry out and groan; but the dead are quiet. The knife had done its work: escape might be surer for the assassin. That's the logic of ghouls.