“We’ll get at the oars again,” said the corporal. “I don’t know how long this tunnel is, but it must end somewhere. If we can reach the outlet and find no Germans there, we’ll have a chance to get back to our lines by land. If not, we’ll have to give these fellows a fight, no matter by how many they outnumber us. I only wish we had more ammunition. A few more shots and we’ll be through.” “We’ve got our knives anyway,” said Tom, “and Heinie hates knife fighting at close quarters.” “I’ve got a hand grenade,” put in Frank. “I picked it up as we were coming away from camp, on the chance that it might come in handy in case we were discovered.” “Good work,” said the corporal approvingly. “But now we’d better start. Waldon and I will take the oars, so as to give you other fellows a rest. Make as little noise as you can but work fast.” They bent to their work, quickened somewhat by the faint sound of oars which told them that the enemy was approaching. CHAPTER V A MASTER STROKE With fresh arms at the oars, they hit up a rapid gait, which in that unknown passage was not without its dangers. The darkness was so intense that they could not see a foot ahead of them, and they dared not use the flashlight for fear it would betray their location to their pursuers. “Let’s hope this tunnel is straight all the way through,” muttered Tom. “If there’s a winding in it and we bring up against the sides it may send us all to kingdom come.” “Right you are,” returned Frank, “but there’s no help for it. We’ve got to take our chance.” He had scarcely gotten the words out of his mouth when what Tom had feared came to pass. The boat smashed head on into the rocky wall where the tunnel described a curve. There was a grinding of oars, a splintering of planks and a startled exclamation from the Army Boys. Luckily Frank and Tom had been sitting in the stern of the boat, and, though they were badly shaken, escaped the full force of the blow. Billy and the corporal were thrown from their seats into the bottom of the boat. The bow was smashed in, and a great jagged hole in the side opened the way for a flood of water that rushed in. In a moment the boat had sunk to the gunwales. Another moment and she had gone under the surface and the four occupants found themselves floundering in the water. All were expert swimmers, and the ducking meant nothing in itself. But the loss of the boat might well mean the loss of their liberty or their lives. They swam to the rocky side nearest them and clambered up on the bank. The path along the canal was a narrow one and the wall of the tunnel rose up perfectly smooth on the further side of it, affording no opportunity of concealment. The corporal gathered them around him. It was time for quick thinking for the sound of oars had grown plainer and the enemy would soon be upon them.