From the solitary window of their room the prisoners were able to witness many of the movements of the troops. The square in front of the range of stores was packed with transport wagons, both motor and horse. The horses were picketed in lines between the regular rows of vehicles. The drivers stood by their charges, instead of being billeted on the inhabitants. Everything pointed to a hurriedly resumed journey.
Presently Kenneth and his chum noticed that the Germans were deeply interested in something above and beyond the storehouse in which the lads were quartered.
A few men would point skywards, others would follow their example, till every soldier in the square was gazing in the air. Then above the hum of suppressed excitement came the unmistakable buzz of an aerial propeller.
"Air-craft!" ejaculated Kenneth.
"Taubes, most likely," added his companion; "otherwise the troops would be blazing away instead of merely looking on."
The words were hardly out of his mouth when the scene underwent a complete change. Horses plunged and reared, some falling and kicking madly on the ground. Men ran hither and thither, seeking shelter, while several of them pitched upon their faces. Yet not a sound was heard of an explosion. A mysterious and silent death was stalking amidst the German transport. Overhead the drone of the propeller increased, yet the aeroplane was invisible from the lads' outlook.
Something struck the stones of the courtyard a few feet from their window. It was a small featherless steel arrow, one of thousands that a French aviator had let loose upon the astonished and terrified Germans.
Simultaneously there was a crash in the room. Turning, the occupants made the discovery that three of the darts had completely penetrated the tiles of the roof and had buried themselves three inches deep in the oaken floor.
"Keep close to the wall," exclaimed Kenneth; "it is the safest place."
"It's all over now," announced Rollo after a brief interval. "There she goes!"