"Signal of some sort," replied Roger. "Guess we'd better get on our feet. The attack may be coming."
"Shall we go back and report this?"
"No, they must have seen it as soon as we did. We're only to report if we see any of the enemy approaching this post."
They waited. Another rocket—a green one this time—soared aloft. And then with a suddenness that was startling, a terrific firing broke out from the German lines. "Here it comes—the counter-attack!" cried Bob.
As he spoke he and his companion saw a dark, massed body moving toward them.
"Come on!" cried Bob. "We've got to report this!"
But before they had time to run back more than a few paces they were surrounded by an attacking party of Germans. On either side of Bob and Roger there was fierce fighting now going on. The two lads who had been on duty in the listening post felt themselves caught and their rifles wrested away before they had a chance to use them, and then they were dragged over toward the German trenches.
"What's it all mean?" gasped Bob.
"We're captured!" said Roger. "Keep still! Don't give any information no matter what they do! Keep still!"
"I will!" said Bob grimly.