"I assure you," said the lieutenant, "that there is an army of the United States in France, despite your unbelief. Why should it seem so strange?" "But you couldn't possibly have gotten over here," persisted the prisoner. "Why not?" asked the American. "Because our U-boats would have stopped you," was the reply. "No use," murmured Frank to Bart. "Nobody home." "Padded cell number nine hundred and ninety-nine," whispered Billy. It was of no use to argue against such credulity, and the lieutenant gave it up. The prisoners were marched back to camp, where the news of their coming had preceded them. It created a great sensation, and was the main topic of conversation for many days thereafter. "It's been a red letter day," remarked Bart that night, as he prepared to climb into his bunk. "You bet it has," agreed Frank. "We bagged a Zeppelin!" Two days after these momentous events, a stir of expectation ran through the camp. Evidently some important move was in prospect. What it was, the rank and file did not know, but rumors and conjectures ran riot. "There's something big coming, boys," said Frank, one night after supper. "That's plain enough," agreed Bart. "But I'd give a lot to know just what it is." "The corporal gave me a private tip," replied Frank. "He didn't go very far into it, but from what he hinted I have a hunch that none of us will go to bed to-night." "What?" they cried, in chorus. "That's what," returned Frank. "But of course it may be a false alarm. Wilson himself wasn't any too sure." An hour later the bugle blew, but this call was not for "lights out." It was the command to "fall in." Sudden as it was, the high state of discipline the men had reached was shown by the fact that there was no confusion. As precisely as veteran soldiers they fell into line by companies and platoons and waited for the order "Forward, march!" The order was not long in coming, and as quietly as ghosts, with no band to lead them, the regiment swung into step and started off. "We're on our way to the front," whispered Frank to Bart, who marched on his right. "Off to the trenches!" agreed Bart. "Well, I'm glad the waiting time is over. Now, we'll have a chance to show what kind of soldiers we are." For three whole hours the march went on without a halt. The night was clear although there was no moon. As the ground was dry and springy the going was good. During that last hour the signs had multiplied that they were approaching the scene of battle. They passed by bits of woodland where every leaf and twig had been stripped from the trees by shell fire, leaving only the scarred and ghastly trunks. They went through villages, or what had once been villages, but were now only heaps of crumbling stone with, here and there, a shaky wall left standing.