"Advance," he said with a breath of relief.

A moment later the boys were safe back among their own men.

"If the Germans had been as watchful as our own sentries, we would have
had more trouble," said Hal.

"Oh, I don't know," was Chester's reply. "I saw a German sentinel, but
he didn't see me in the darkness."

"It was his business to see, however," declared Hal.

"Well, that's true. But now let's listen and seen if we can overhear
anything of importance."

Chester clapped the little receiver to his ear. Hal became silent.

Ten minutes later Chester removed the receiver from his ear.

"Nothing doing," he said. "I can hear some of the men talking, but
they are evidently playing cards."

"Let me listen a while," said Hal.

Chester passed the receiver to his chum, and the latter listened
intently. For some moments he heard nothing save the jabbering jargon
of German troopers apparently interested in a card game. He was about
to take the receiver from his ear, however, when another voice caught
his attention