They had hardly progressed a hundred feet further when the unlucky Slim tripped and went sprawling on the ground with a pained but suppressed grunt.
"Sh-h-h-h!" warned Lieutenant Mackinson in a whisper, while Tom Rawle, quietly chuckling at the fat lad's misfortune, aided him to his feet.
"Down flat!" said Mackinson again, as he discerned several shadows moving across a space a considerable distance to the north of them.
For fully ten minutes, which seemed like an hour, they lay there, not daring to move. They watched the enemy scouting party get a like scare, and then, after what seemed to be a whispered consultation, turn back to the German lines.
"What did you fall over?" the lieutenant finally asked of Slim, in a scarcely audible tone.
"I just found it," replied Slim. "It's a wire. Here, let me have your hand." And he guided the lieutenant's fingers to that which had been the cause of his downfall.
"Copper!" exclaimed the lieutenant. "Hoskins, let me have that kit."
And without the aid of a light he extracted from the leather case which Hoskins gave him a very small telegraph instrument. The instant it was attached to the wire the receiver began to tick irregularly.
Neither Rawle nor Hoskins understood German, but to the others they were words easy to translate.
They had accidentally struck an enemy wire and had tapped it! That part of the message which they had intercepted read: