They were sheltered now and safe from observation. They could, nevertheless, see the German column strung out along the road. It seemed to cover at least two or three miles of the road, and there was no way of being sure that there were not more men.

"I think they've got pretty nearly five thousand men," Frank decided finally. "They're in light marching order, for Germans, too. No camp kitchens--nothing. Only what the men themselves are carrying. They're making a forced march to get to some particular place. Queer to use infantry, though, but I suppose they couldn't get horses through with whatever trick it was they played."

"They're beginning to turn off," said Henri. "See, the head of the column is slipping through that field over there. They must know this country as well as I do or better. That's a short cut that will take them to Hierville."

"I don't believe they're going to Hierville or any other village now,"

said Frank. "Tell me, are those woods I can see in front of them at all thick?"

"Yes, they're old, too. They've been preserved for a long time. That's the oldest part of the old park of the Chateau d'Avriere. It was one of the castles that wasn't destroyed in the revolution."

"Well, they're going to take cover in those woods. This is all a part of a mighty careful plan, Harry. I think they have turned a real trick. If the French or the English knew that the Germans were in any such force as this so far south and west as this they would be acting very differently, I believe. Their aeroplanes have certainly failed them here."

"They're on the line of retreat, if we were beaten again in that battle we've been hearing all afternoon."

"I don't think it was a real battle at all, Harry. I think it was just rear guard fighting. But I tell you what we've got to do. We've got to get through and tell about these troops. Of course, they may know all about them at headquarters, but it doesn't look so. We had better wait here until we make fairly sure of what they're going to do and until there isn't any more danger of our being seen, too. They'll have scouts out all around them. We were mighty lucky to get through so long as we have. But it's going to get dark pretty soon, and then we ought to be safe."

They lay in their improvised shelter. It took the Germans a long time to pa.s.s, but at last the road below was free of them, and the last of them slipped into the sheltering obscurity of the woods.

"We ought to find out if they're staying there, or if they are still moving on," said Frank. "It's risky, but I think we ought to take the risk. You stay here, Henri. I'll try to get around, and come back."

"Why should I stay here? If there's a risk, why shouldn't I take it just as well as you?"

"Because one of us has got to get through. If I'm caught, you'll still be here and able to get through to headquarters with what we've found out already. And the reason I'd better go is that I'm an American. If they catch me they're not so likely to hold me."

"But I don't think it's fair for you to take the risk. I ought to do it," said Henri, stubbornly.

"I don't care what you think," said Frank, "I'm going. Au revoir, Harry!"

"Wait a minute! How are you going to find out?"

"I'll try to skirt the wood."

"You needn't do that. Keep straight on the road we were taking, instead of turning off at the foot of the hill. About half a mile beyond the crossroads the road rises again, and you'll find a windmill. If you climb to the top of that you can see beyond the woods, and you ought to be able to tell if the Germans are moving out of the woods."

"Splendid!" said Frank. He admired Henri's readiness, once he had made up his mind that Frank was going alone, to help him with his greater knowledge of the countryside. Some boys would have been sullen, and would not have volunteered that information, he was sure.

Before Frank started on his lonely errand, he carried Henri's bicycle back of the hedge. Then he mounted his own, and coasted down the hill.

His object was to seem entirely indifferent, should some German scout or straggler spy him, but plainly the Germans had decided to leave the road uncovered.

"I guess they decided it was better to risk being surprised than to give themselves away," he said to himself. "Otherwise they'd have been pretty sure to leave an outpost of some sort here because this road looks like just the place for troop movements. It looks more and more as if they had really managed to make a secret of this column."

It did not take him long to find the windmill of which Henri had told him. The place was deserted; there was no one to oppose his entry. And, when he reached the top, he found that there was an excellent view of the country for several miles, a much better one than they had had from their shelter on the hillside above the Germans.

He could see the woods into which the invading troops had disappeared, looking dark and mysterious in the deepening twilight. There was no sign of life about them; no smoke rose above the treetops. And no Germans were beyond them. Then his guess had been right, he decided. They had made for those woods to obtain shelter, and they relied upon the fact that the allies did not know of their presence. It was a daring move; it might well have been successful, save for the accident of the two boys who had observed it. Indeed, even now there was a chance, and something more than a chance, that the German object, whatever it was, might be attained. Frank and Henri were a long way yet from having reached the British headquarters. Unknown dangers and obstacles lay between them and their destination.

"With the German attack developing so quickly as this, we don't know where we may not run into them," mused Frank, as he descended from the windmill and mounted his wheel, preparing to start back to join Henri.

"They may be anywhere. I don't want to see them win, but they certainly are wonderfully good fighters. They have good leaders, too."

When he reached Henri he found that his French comrade was lighting the lamp of his bicycle. With a laugh he blew out the flame.

"But it's dark and we'll be arrested if we ride without a light," said Henri, protestingly.

"That law was made for peace, not for war," said Frank. "When we know as little about where the Germans are as we do, I'm not going to take any chances. We'll ride with lights out, thank you. Come on!"

As they rode along in the growing dusk, close together, Frank told what he had seen.

"That was a good guess, then," said Henri. "But, Frank, how can they know so well what to do? You would think that they had been brought up in this country, those German officers!"

"They might as well have been," said Frank. "I've heard stories of how they prepare for war. They have maps that show every inch of land in this part of France. They know the roads, the hills, even the fields and the houses. They have officers with every regiment who know where ditches are that they can use as trenches, and who have studied the land so that they recognize places they have never seen, just from the maps that they have studied until they know them by heart. And it isn't only France that they know that way, but England, and some parts of Russia, too. Why, I've even heard that they've studied parts of America, around New York and Boston, almost as thoroughly."

Henri cried out in anger.

"That is how they have behaved!" he cried. "They have been planning, all these years, then, to crush France!"

"Oh, cheer up, Harry," said Frank. "I guess you'll find that your French staff officers have returned the compliment. Unless I'm very much mistaken, any one of them could tell you just as much about the country in Alsace and Lorraine, and all through the Rhine Province, as the Germans could of this section. It wasn't so in the last war. Then French officers were losing their way in French territory. That was one reason why the battle at the Speichern was lost--because French reinforcements lost their way. But this time France got ready, too."

"Shall we still make for Le Cateau?"

"There's nothing else to do, until we find out that the staff has changed its location."

Riding along in a light that made men out of the shadows of trees and regiments of the shocked corn in the fields was eerie work. But neither of them was afraid. They were fired by a purpose to serve the cause in which they had enlisted. And they were thrilled, too, by the knowledge of the German force upon which they had spied, themselves unseen.

And then all at once, out of a dark spot in the road, appeared a man, holding a horse.

"Halt!" he cried, in a guttural voice.

They obeyed, perforce. And when they were close enough, they saw that he was a German cavalryman, one of the dreaded Uhlans.

CHAPTER X

THROUGH THE LINES

For a moment Frank's heart sank, but suddenly, a hoa.r.s.e laugh surprised him and revived his spirits. It was the Uhlan. He was laughing at them.

"Kinder!" he said, deep down in his throat.

"Nothing so alarming in this," thought Frank, experiencing quick relief, and awaiting the Uhlan's next words.

"I have my way lost," he said, in a guttural English. "Kannst du Englisch sprechen?"

"I am an American," said Frank, at the same time nudging Henri, and hoping that he would understand it as a signal to keep still. "Where do you want to go?"

"That matters not," said the German, cautiously. "Only tell me, which way from here is Amiens?"

They told him.