Other ears than theirs had heard that firing, too. As they rode along they saw a cloud of dust before them, and soon men and horses emerged from the dust.
"Let's hide in the hedge along the road," said Frank. "Come on—they'll never see us."
"But they won't hurt us, Frank. They're English—our friends."
"Probably they are. But how do we know? They may be more Germans."
"Oh, I never thought of that! If they are—"
"Yes, if they are, it's good-bye to Captain Hardy and his supplies. But we can't help it. We've already done all we could for him."
They watched the oncoming cavalry, but even at a little distance, what with their speed and the dust, it was impossible to tell to which army they belonged. They were either English or German; that was all that could be certain. And that could be deduced from their khaki uniforms. There were no colors to emerge, bright and vivid, from their dun mass; no points of steel, on which the rays of the sun might shine and be reflected.
"If they were French we could tell," said Henri, proudly. "We could see their red and blue uniforms and, if they were cuirassiers, their breastplates!"
"Yes. The French are far behind the times in that," said Frank, a little impatiently. "Nowadays armies don't try to act as if they were on dress parade. They wear uniforms that can't be seen any great distance away."
"The French army fights in the uniform in which its famous victories were won," said Henri.
"And it gets killed in them, too," said Frank. "Gets killed when it doesn't do any good. But that doesn't matter now. Ah, they're English! I can see that now. We needn't tell them to hurry—they're going for all they're worth now. They've heard the firing and are hastening."
The English horsemen swept by. They were riding low in the saddle, urging their horses on. Each man carried a carbine, ready to dismount at any moment and give battle as seemed best. In five minutes they had swept by.
"Two troops," said Frank. "Well, that ought to be enough, though there's no telling how many Uhlans there were. Ah, here come some more!"
This time it was a battery of light artillery—four guns, going along almost as quickly as the cavalry had done.
"That ought to settle it," said Frank, with satisfaction. "Even if they run into a brigade of Uhlans, the guns ought to do the trick. I don't believe they had any guns or we'd have heard them by this time."
"They're still fighting back there," said Henri, as they wheeled their bicycles back to the road. "I can hear the firing."
"Yes, and I think it must be a pretty lively skirmish, too," said Frank. "Captain Hardy would keep them at it. Listen! The Uhlans must outnumber them three or four to one. I hope the others get up in time."
A few minutes gave assurance that they had. They heard the firing still more loudly; then, a few minutes later, the heavier sound of the guns chimed in. And then there was silence behind them.
"Score one for our side," said Frank. "We know a little more than we did before, too. I think it's a safe guess that the Germans aren't in this direction. We can go along without worrying about them."
As he said that they were coasting down a little hill, at the bottom of which, Henri had said, another road crossed the one on which they were riding just around a little turn in the road. And as they took that turn, their feet off the pedals, they almost fell off their wheels in astonishment. For the transverse road was gray-green with soldiers; soldiers with spiked helmets, marching south!
A moment later they did fall off their wheels, deliberately, and at a common impulse, because it was the only way there was of stopping before they were in the midst of the German infantry. There was just a chance that they had not been seen and they took it, and fled to the hedge again, leaving their bicycles behind. There was no time to bother about such trifles now. The thing to do was to make good their escape, if they could.
"Whew!" said Frank, whistling. "That was a close shave, if you like! Where on earth did they come from? And how is it they didn't see the English cavalry?"
"Perhaps they didn't care, if they did see them," said Henri, wide-eyed with astonishment. "Look, Frank, there must be thousands of them! Where can they be going?"
"Where did they come from? That's more to the point!" said Frank, vastly excited. "I know! They got the railway—that's what they did! They must have come through Arras. Jove, though, they took a terrible risk, Harry! Because, no matter how many of them there are, they can't even begin to compare with the allies in numbers—not around here. But how can they be here without being seen? What are our aeroplanes doing?"
"I haven't seen one all day—not since we left Amiens, at least," said Henri. "But I know where they are—flying over the enemy's lines, trying to locate the guns exactly. That's what they try to do, you know. They decide just where a masked battery is, and then our fellows can drop their shells right among their guns. The gunners can't get the range properly any other way. There isn't any powder smoke to help them any more, you know. So I suppose that's where they are."
"Then I tell you what I think happened. I think they cut the railroad, or, rather, they didn't cut it. I bet they ran those fellows down there through on trains—right through our army."
"How could they do that?"
"Easily—no, not easily. It wouldn't be easy at all. But it's possible. They've caught a lot of our men, haven't they? Well, couldn't they use their uniforms so that it would look as if it was a French or an English train? Let me have your field glass. It's better than mine."
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 pass, 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.