This was a chance, however, that they had to take. But the first thing to do was to dispose of the sentry.
The path along which he seemed to be coming was bordered with a small and uncared-for hedge.
In a hurried whisper Wilson gave his commands.
"You, Sheldon and Raymond, creep ahead and lie on opposite sides of the ledge. When the sentry comes along, close on him at the same time. Keep him from making a noise if you can. The one thing is to be quick."
Frank and Bart glided along and took up positions opposite each other.
"You grab his gun, Bart, and I'll make for his throat," whispered Frank.
The sentry came on unsuspectingly. Lithe as panthers the boys leaped upon him, Bart grasping the gun, while Frank's sinewy hands fastened on his throat.
There was a muffled exclamation and a short sharp struggle. Then the sentry lay on the ground unconscious, while Frank and Bart hastily improvised a gag, and bound the man's hands and feet.
"Good work," commended the corporal, as Frank and Bart rejoined their comrades. "That was the most ticklish part. The rest ought to be easy."
But he was mistaken, for just then the door of a dugout in a small trench opened, and two men came out with lanterns. It was evidently the corporal of the guard who had come out with a private to relieve the sentry.