It was quite natural, therefore, that whenever the boy heard the awesome scream of a shell a little louder than usual his heart beat faster.
Going this way and that and concealing their movements in every possible manner, the five reached a deep trench, which zig-zagged across a field absolutely bare of vegetation. One by one they leaped into it, and, in single file, continued steadily along.
"Don't forget to keep your heads down," cautioned Lieutenant D'Arraing.
"Never fear!" said Don. "We won't do anything to bring about an inglorious end to the expedition."
Presently the trench led upward over the slope of a hill, and when the top was reached turned sharply to the left. A few yards further on, around a bend, the boys discovered the observation post, roofed over with corrugated iron. Right beside it was a dugout.
"Here we are," spoke up Lieutenant D'Arraing. "And if I am not mistaken our being here won't be a very good thing for the Boches."
Not far away, close to the parapet of the trench, stood a row of bushes. With a wave of his hand, indicating these, the captain exclaimed:
"I think it will be safe for you, boys, to take a look from there."
While the operator by the entrance to the dugout was adjusting the telephone to the wire Don and Dunstan, both provided with field-glasses, cautiously moved forward, with the lieutenant by their side.
"Now we are ready for the fireworks!" muttered Don Hale, grimly.