The last hundred yards they crept, lying flat and motionless whenever a flare lit the sky. They were not frequent, however, and the boys made good progress. When they reached the mound, Porky, who was the best climber, crept to the top. He used the most infinite caution, and there was not a sound to betray his slow, sure progress. Gaining the top, he found what he had expected to find. A sodded opening, like a double trap door, operated from the inside, was slightly opened for air. So cleverly was it arranged with small bushes and grass growing on the trap doors, that it would have been impossible to detect it. Porky felt cautiously about the edges. Then he listened. From below came an unmistakable sound--the noise of a couple of men snoring. The sound was so muffled by the thick steel walls, the earth and stones and sod outside them, that they were able to sleep without fear of detection. Porky shook his head admiringly. He was forced to acknowledge that the ingenuity of the foe seemed to know no bounds. Again he tried the trap doors. They were balanced to a hair and moved upward at his touch. He felt in his pocket, arranged something in either hand, then swung the doors both upward. It would be untrue to say that a flash of doubt did not pass over the reckless boy at that instant. He thought of the General and of the way in which that great man trusted them to do their part in keeping out of trouble. He had surmised that there were three men below. There was room for a dozen. He had taken it for granted that he and Beany could pull off a stunt that instead might end in their immediate death or worse. But there he was, perched on the top, the heavy trap doors swinging wide, and below in the dense darkness the sound of men snoring. Porky took time to listen. There were snores from two, that was clear, and still another man talked and muttered fretfully in his sleep. Porky could hear no others. He took a long breath, leaned over the opening, and turned a flashlight below. As though electrified, three big men sat up and blinked in the glare of the flashlight. Two of the men cried, “Kamarad!” and instantly held up their hands. The third said calmly, “Thank the Lord! I surrender!” and stood up. “Not so fast!” said Porky in his deepest tones. He fiddled with the button on his flashlight. The light wavered. Porky kept his face to the men and called back over his shoulder: “Sergeant, something’s wrong with my flash. Send up another!” “Yes, sir!” answered Beany as gruffly as possible from below. He waited a moment, then scrambling up passed his flash to his brother. Porky put his in his pocket, and bent the light on the men below. An ax stood in one corner with a coil of rope. In another corner was a rough table loaded with strange instruments that Porky did not understand. “Turn out your pockets!” he commanded, and three revolvers were tossed up, one after the other.