Tom nodded his understanding and the rest left him, dropping flat on the bank as soon as they reached the top and worming their way over the space that intervened between them and the patch of woods some distance beyond. The strain on nerves and muscles was tremendous and it was with a sigh of relief that they reached the shelter of the woods. Here they could rise to their feet, although even this required the most extreme care. They were by no means assured that it was a friendly shelter. It might contain machine gun nests or strong forces of the enemy. Five minutes of the most intense silence and listening passed before they dared even to whisper to each other. Convinced at last that no one was close at hand, the boys drew near the corporal for his final instructions. “We’re certainly in luck so far,” he breathed. “The only explanation of the failure to have sentries here is that they had no idea today that they were going to be driven back so far as to have to cross the canal. They came over helter-skelter and they’ve been so busy in blowing up bridges and getting their rattled forces together that other things have had to wait. But it’s only a matter of time before they’ll have guards set here, and we want to get back before that happens, if possible. Bring your watch hands close to mine and let’s compare so as to see that we have the same time.” They did as directed, and the illumined faces of their radio watches showed that their time was practically the same. “Five after ten,” remarked the corporal. “That gives us two hours until midnight. At twelve o’clock sharp, wherever you happen to be, start back for the boat. You’ve each got a compass and you can come pretty close to the place, and the owl signal will do the rest. Find out whatever you can as to where the enemy has his battery positions, where he has gathered his greatest force, and where his wire entanglements are weakest. You’ve got your knives, and if I were you I’d depend on those if you find it necessary. Only use your revolver as a last resort, for if you have to fire the jig is up. “Now we’re going to spread out like a fan. Sheldon, you go off there to the left. Waldon will bear a little away from the canal bank toward the north, and I’ll take the path between you two. I don’t need to tell you that your life depends on your being careful. You know that as well as I do. Twelve o’clock sharp, mind. Good-bye and good luck.” Without another word they separated, gliding from tree to tree and gradually getting further apart, as they followed the general path that had been marked out for them.