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.



CHAPTER X

THROUGH THE LINES

For a moment Frank's heart sank, but suddenly, a hoarse 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.

"And where does the road to St. Quentin turn off from this one?"

"It is the next turn, to your left," said Frank, truthfully.

"Good! Then I will be going. Go home, kinder. You will get into trouble if you stay hereabout."

He vaulted upon his horse, and the next moment they heard hoofs clattering along the hard road, and, looking after him, could see the sparks as the iron clashed with the flint of the road's surface.

"That was easy!" said Frank, with a gasp of relief.

"He was alone," said Henri.

"Carrying despatches, I expect," said Frank. "He wouldn't tell us where he was going, naturally, but I bet he's looking for those other troops we saw. Dangerous work, too. But I wonder where he came from. If there are more Uhlans in front, we may get into trouble."

"Suppose we hide the bicycles near here and go along through the fields? Don't you think that will be better, Frank?" was Henri's cautious suggestion.

"Yes, I suppose it will, though it will be slower, too."

"Of course. But if we are going to be stopped all the time along this road, we'll really save time in the end by doing it."

So they made a cache, as Frank told Henri it should be called, hiding their wheels so that they would have a chance of recovering them if they came back this way. They marked the spot not only by landmarks, but by the stars, which were beginning to dot the sky now.

"There may be fighting here," said Frank. "And if there is, this place may look very different before we see it again. If there is a battle the trees will go, and the fences, and all the houses for if they are not burned deliberately, the shells will destroy them."

"Look, Frank, what is that?"

Henri had turned and was pointing now to the north. There a stream of white light shot into the air, then dropped, and left only its reflection. But in a moment others joined it, and the whole sky to the north was brilliantly lighted. It was like a display of Northern Lights, only nearer and even more brilliant.

"Searchlights, of course," said Frank. "They can throw them on the trenches—and they're good to guard against aeroplanes and dirigibles, too. At night, you see, there'd be a chance for aeroplanes to fly very low and do a lot of damage."

"Can't they hear the engines from the ground?"

"Not always. They have mufflers on a good many aeroplane motors now, so that they don't make any more noise than a quiet automobile."

"I didn't know that. Well, there's one good thing about the searchlights. We know which way to go. Come on."

"All right. The more I think of it, the better it is not to be on the roads. Here in the fields we're a lot less likely to run into stray parties. And I'd just about as soon meet Germans as allies. If they're retreating and having trouble, they might hold us up as long as the Germans would. They wouldn't believe we really had despatches."

For a time they made good, steady progress. The roar of artillery fire in front of them had been resumed, and now it filled the air, proving that they were much closer to the battle. The great waves of sound beat against their ears, making their heads swim at first, but gradually they grew used to it, and could hear other and more trivial sounds—the chirping of night insects and the occasional hooting of owls.

"I don't hear the rifle fire," said Henri, after a time. "Only once in a while, that is. Why is that, I wonder? Are the big guns drowning it?"

"No. Because if that were the reason, we wouldn't hear it at all. I think they don't do that at night. It's just a case of trying to find the places where the enemy's troops are massed, and keeping up a steady fire of shells to drive them out. Maybe the searchlights help. They've been fighting all day, you know, and even soldiers have to have some rest. They have to eat and sleep or they can't keep up the work."

They crossed more than one road, but stuck to the fields, travelling in a straight line as nearly as they could figure their course. When they had decided to join the Boy Scouts, both had studied the stars, since a knowledge of the heavens is one of the most important things about scouting, and they found what they had learned very valuable now. Thus they could keep their bearings, though owing to their desertion of the roads, Henri confessed that he had very little idea of where they were.

"Along the roads one has landmarks," he said. "I have gone all through here, over and over again. My father used to drive this way very often in our automobile."

"Well, we can't go very far wrong," said Frank, cheerfully. "All we've got to do is to follow the old German maxim, 'March on the cannon thunder!' That was their one rule in 1870, you know and a very good rule it proved too."

So they went on. And they still seemed to be a long way from the seat of the heavy artillery firing when a challenge halted them, as they were about to cross a road.

"'Alt! 'Oo goes there?" called a cockney voice sharply.

"Friends," cried Frank, instantly.

"'Alt, friends, while I 'as a look at you," said the sentry.

"Call your officer, please. We are carrying despatches," said Frank.

"I'll call 'im, all right. My word! You ain't nothin' but kiddies, you ain't! 'Ere! Corporal of the guard! I sye! Corporal of the guard!"

He raised his voice in the shout, and a minute or so later a corporal appeared.

"Came up to me, sir," said the sentry. "Said as 'ow they wanted me to call the officer of the guard. Carryin' despatches, they sye they is."

"All right," said the corporal, briskly. "Come with me, my lads. Step smartly when you're told or you may be shot," in a genial voice.

They followed him through a field that seemed deserted, then came to a small cluster of tents, where they stopped.

"Wait here," said the corporal. "I'll bring the lieutenant."

They did not have long to wait before a young officer approached them.

"My word!" he said, when he saw how young they were. "What are you youngsters doing here?"

"We're looking for headquarters, sir," said Frank. "We are carrying despatches from Amiens."

"All right! Give them to me, and I'll see that they're forwarded, my lads," said the officer, with a grin.

"We can't do that, sir," said Frank. "Our orders are to carry them to headquarters—and to give the word Mezieres."

"Ah, that's different, now," said the officer. "Corporal, give me two men to take these despatch-bearers through the lines," came the order.

The giving of the word had made a great change in his attitude. It was plain that before that he had not taken them seriously, but had supposed them to be playing some prank. Now, however, he looked at them curiously.

"Boy Scouts?" he suggested.

"Yes, sir," said Frank. "Detailed to special duty, without uniforms."

"I see! Jolly plucky of you, I call it. I say, you're not French, my lad, are you? How did you get here? Well, never mind! Here's your escort. Be off with you, now."

Their troubles were over now. Within five minutes they were at headquarters. There a weary staff officer received them. They saluted.

"Very well," he said. "Give me your despatches."

Each of them produced his handful of marbles from his pocket, and laid them solemnly before the major. He stared, first at the marbles, then at them.

"What sort of a silly prank is this?" he roared. "Do you think we've nothing better to do than to waste time in jokes? If you were men—"

"We are obeying orders, sir," said Frank, quietly. "Those are the despatches Colonel Menier at Amiens gave us to deliver. He said that only one officer here would know what they meant, and how to get the despatches."

"O, I beg your pardon," said the major. He took down his telephone. "Ask if despatches are expected from Amiens," he said, into the instrument. "And find out who is in charge."

"There is another matter, sir," said Frank. "We saw German troops as we came here."

"Uhlans. Yes, they're all around behind us. One squadron of them was cut up when it attacked a convoy. There aren't many of them."

"No, sir, I didn't mean Uhlans. There is a force of infantry—five thousand men, we estimated—"

"What?" thundered the major, springing to his feet, "You must be dreaming! Where did you think you saw them? And where were they?"

Frank explained.

"It sounds incredible," said the major, frowning. "Come! I'll take you to General Smith-Derrien. If that's true, it's highly important news. Here, show me on this map just the place where you say you saw them."

Frank and Henri pointed at once to the wood in which the German infantry had vanished, then followed the major out of the room.



CHAPTER XI

AN UNEXPECTED CHANCE

The first impression they had of General Smith-Derrien was of his absolute calmness. The major had been excited when he heard the report of the German infantry in the woods. But when they entered the room in which sat the British general who was responsible for the retreat, as they guessed, they saw a quiet-faced man with smiling eyes, who listened attentively to the reports of the officers who were constantly hurrying up to him, spoke a word or two in answer, and turned, imperturbably, to the next comer.

Their guide left them near the door.

"Wait a minute here," he said. "I'll tell the General your story. But he'll want to speak to you himself. He always does."

Frank watched the British leader closely as he turned to the major, who now went up to him. If the news moved him, he gave no sign of his emotion. Instead he nodded quickly, once or twice; then he looked over toward Frank and Henri. The major turned to them, beckoning, and they went up. General Smith-Derrien was sitting at a table. Before him was an ordnance map of the section covered by his operations.

"Now tell me exactly what happened, as quickly as you can," he said. "You saw these Germans—just where? Point it out on the map. Give me your position and the road they took."

Frank and Henri studied the map a moment. They traced their own course from Amiens; soon they found the spot. The map was on a very large scale, and it showed the hills and a great deal of detail. It was easy to explain just where they had seen the Germans.

"They went into the woods, you say," said the general. "But why did you think they stayed there? Why shouldn't they have gone on?"

"I went along the road to a spot where I could see beyond the woods, sir," said Frank. "And there was no sign of them."

"You did? That was excellent—regular scouting. Oh, I fancy I understand! Boy Scouts, are you?"

"Yes, sir," they echoed together.

"Well, if your information is exact—and I have no reason to doubt it, of course—you did a very fine piece of scouting, and I shall be glad to see that you get the proper amount of credit for it, when the time comes. Now your information is most valuable. But before I can act on it, I must be absolutely certain that it is accurate. Will one of you help one of my scouts to determine this?"

"Let me go, sir," said Frank, quickly. "I was the one who saw the other side of the woods—"

"But I know the country best," protested Henri. "And—"

"I think you'd better go," said the general to Frank. Perhaps he thought Frank was English; in any case he selected him. "I don't think it will be dangerous at all, or I shouldn't let you go. We haven't started using boys in this war yet. Major, you will see to it that a start is made as soon as possible!" turning to that officer.

The major saluted.

"Yes, sir, at once," he said. "The one who does not go can deliver the despatches they brought from Amiens—a handful of marbles!"

"Eh? What's that? Those are the despatches from Colonel Menier. I'll take those!"

Plainly, since he knew of them, he was the officer to whom they should be delivered. So Frank and Henri, not without some misgivings, since the major's annoyance at the sight of the marbles had rather depressed them, handed over their marbles. General Smith-Derrien picked them up, weighed them in his hand, and finally selected two, to the undisguised amazement of his staff. But when he pressed a hidden spring, and each marble flew back, showing that it was hollow, cries of admiration came from those who were close by.

"Very well. They are in good order," he said, after a glance at the thin but tough paper. "I will send an answer by the scout who remains here."

The major was already moving toward the door, and Frank, with a quick grasp of Henri's hand and a salute for the general, followed him. He was sorry for Henri's disappointment, but he had made up his mind when they left Amiens that whenever possible, he himself would take any risks that were to be run. No one would care greatly if anything happened to him, since his parents were dead, and his only other close relative was his uncle, of whom he had seen very little. But Henri's mother was alive, and, moreover, she had troubles enough. Her husband was at the front, and there was no telling whether or not he would ever return.

"Come along, young 'un," said the major. His name, Frank learned, when a passing officer spoke to him, was Cooper. "Know what you're going to do?"

"I'm to help a scout to determine the position of the Germans we saw," said Frank.

"Yes, but how? In an aeroplane, my lad! I envy you. They've never let me go up in one of the blooming things yet—and just because I happen to be assigned to a special job here with the staff. A lot of fun this war is going to be for me! We've been at it pretty nearly a month, and I haven't been under fire yet!"

Frank found it hard to conceal his delight. He had always wanted to have the experience of riding in an aeroplane, but never before had he seen even a remote chance that it would be gratified. Now he was to have fulfilled one of his most cherished ambitions—and in what a way! To fly with one of the wonderful aviators of whom he had been hearing ever since the war began, and over hostile territory. Risk! What if there was?

In his own room Major Cooper sent an orderly flying, and in a few moments he returned, followed by a spare, tall man in a uniform differing slightly from that of the regular troops. He wore a heavy sweater, and on his head was a headgear resembling, Frank thought, that worn by football players in America.

"You sent for me, Major?"

"Yes, Captain Greene. You'll have to make a flight to-night. This lad is one of two Boy Scouts who have reported seeing German infantry in rather considerable force south and west of our position here. He will show you on the map just where he says they are lying up. The general wants to verify this report or disprove it as quickly as possible. Your orders are simply to make a reconnaissance and to run no avoidable risks. If it is possible, ascertain the facts without betraying your own presence. I have detailed you because you have a silent motor."

"Very well, sir," said Captain Greene. "Now, then, my lad, sharp's the word. Show me just where you say these Germans are."

For the third time Frank pointed out the spot on the map, and the flyer whistled.

"Don't wonder you want to know where they are!" he said. "If that's so, it's a pretty big sell for us flying chaps—eh, what? We rather fancied there wasn't a chance for them to do anything that we didn't know all about as soon as it was done."

"Exactly," said the major, rather dryly. "Well, here's your chance to make up for errors of omission. Get the facts, and get back as quickly as you can."

"All right. Double quick, young 'un. What's your name, eh? Might as well be sociable!"

Frank told him, and liked the tall aviator immensely. But there was no more talk between them as he followed the captain to the outside. He had all he could do to keep up with the Englishman's great strides without trying to talk too. Greene led the way to a park-like enclosure, where, under shaded electric lights that lit the ground fully but were so screened that no betraying flashes showed from above, a dozen aeroplanes stood, gaunt and ghostlike in the night.

"See those lights?" said Greene. "If one of those German Johnnies in a Taube came along he could make a lot of mess by dropping a couple of bombs down here. An aeroplane's delicate enough as it is. A bomb will put it out of business in no time. Here we are! Wait till I try the motor and see to my tank. If you run out of petrol at five hundred feet you can't always find a garage where they'll sell you more!"

The tank was full, however. His mechanic had seen to that. And the engine responded beautifully to the first test.

"All right," said Greene. "In with you! Ever been up?"

"No. This is my first trip," said Frank.

"Easy enough, if you don't get scared. Keep perfectly still. No matter what happens, don't touch me or anything except the grips for your hands that you'll find there. She's apt to rock and kick like a broncho sometimes but you can't fall out, because you'll be strapped in. Remember, now, don't touch me and don't touch any levers or anything else you see."



CHAPTER XII

THE MONOPLANE

Looking down from above, as he was doing, it was hard for Frank to keep his bearings at all. Naturally, everything looked very different. He had been used to looking up at houses, and had had them in one plane. Now everything was flat before him. In the day time the resemblance of the country as he now saw it to a map might have helped him. But at night, even on a clear night, things were blurred. Fences and roads ran together confusedly. And this night was not clear. The day had been fair, but now clouds were coming up.

"We'll have some rain, hang it!" said Greene. "The firing seems to bring it. At least that's what they say. Wonder if it's true? I suppose it might."

"I should think it might be a good thing," said Frank. "It'll make it harder for them to see us, won't it! And that ought to help us."

"Yes, but it'll make it a good deal harder for us to see what we're after, too. Cuts both ways, you see. Still I don't mind as long as we don't have fog or wind, and I think I'd rather have the wind. You know where you're at with wind, anyway. In a fog—Lord! You've no idea what a thing fog is until you've tried to make a landing in it."

With the motor muffled down, they were able to talk easily. In the earlier days of aeroplanes the motor made so much noise that anything like a sustained conversation was impossible. But now the motor only purred gently in their ears, just like that of a motor car. For military purposes the silence thus obtained more than made up for the slight sacrifice of power. The more old-fashioned 'planes, many of which were still in use, advertised their presence to an enemy as soon as they came at all near. But this new type, largely used by the British and the French, as Frank knew, had to be seen before they were in any danger, so silently do they wing their flight.

"Talking about fog," Greene went on, talking as indifferent as if they had been on solid ground, "I had a nasty experience just before Kaiser Bill started this trouble. Went up at Sheerness, for an experimental flight in this same 'plane. First time I'd had her out, and I didn't know her very well. And one of those old-fashioned sea fogs came rolling in when I was ten miles from anywhere. Never saw anything so sudden in my life!"

"How did you find your way, sir?"

"I didn't! I just went up and up until I was above the fog and in the sunlight. You can do that, you know. But that was a queer fog—rose a whole lot. Anyway, when I got above it, it was precious cold. And the sun didn't do me much good. I'd got lost, so far as my bearings below were concerned, making spirals as I went up. What I hoped for was to find out something when I was above the fog."

"How was that? You mean that the fog would only spread over a certain distance?" he asked.

"That's it exactly. Only I didn't know that fog! So far as I could tell, it spread over all England and Ireland, too, with some left over for France! Only one thing for it, of course. I knew I'd get away from it if I kept on flying. So I steered by the sun as well as I could, and kept on until my petrol began to run short, and a cylinder began missing. And then, just as I was wondering whose windows I'd break when I went down, it began to thin out, and slipped away as quickly as it had come. And I was right above the golf links on Wimbledon Common. I volplaned down, and landed on a putting green, and an old colonel who'd been invalided home from India said I'd done it on purpose, and he was going to have me court-martialled!"

Frank laughed heartily at the story. But at the same time, he suspected Captain Greene's purpose in telling it. He thought the captain wanted to keep his spirits up, and make him forget that he had never had a flight before, and he admired and liked him more than ever in consequence, even though, as he told himself, it wasn't necessary.

"Hello! I think we're getting near your spot, young 'un," said Greene, abruptly. He dipped down, and Frank peered down to see where they were.

"Yes," he cried, in assent. "There's the hill we were coming down when we saw them, just as we rounded that turn. That's the road they were marching along, and there, over to our left, are the woods. I wonder if they're still there."

"We'll soon know," said Greene. "Now for a little climbing. I'm not afraid of being hit, but orders are to find them without being seen, if we can manage it. So we'll try the high spots for a bit."

At once the monoplane began climbing, ascending in great spirals. Frank was absorbed by the sensation. He found that he could see the ground receding without feeling any qualms, and said so.

"You're lucky," said Greene, briefly. "Made me feel queer first few times I tried it, I can tell you. You're probably a born flyer—and the chances are you'll never do much of it, I suppose! Always the way!"

Frank, looking down, saw that they were moving away from the woods which they were to reconnoitre, and mentioned it.

"Got to," said Greene, briefly. "Then we'll fly back. We can't climb in a straight line. When I went out for altitude once, I made twelve thousand feet, and when I finished climbing I was nearly fifteen miles, in a straight line, from where I started. Let's see. Got that flashlight I gave you? Play it right on the board there till I tell you to stop."

Frank obeyed, shooting the little spear of light on the various instruments in front of the aviator.

"All right. Hold it there. My barograph, you see. Gives me my height by showing the change in atmospheric pressure. That's how we calculate height. Not very exact, because all sorts of things vary the pressure. But it's near enough. A thousand feet! That's good enough. I don't believe they're looking for us. We don't usually scout behind our own lines."

Now he brought the monoplane around in a great sweep and flew straight over the woods. But, though Frank looked down through powerful navy night glasses, of the sort that are used for look-out duty at sea, he could see nothing.

"Clasp them around my head—so," said Greene. "See the trick? All right! Now I'll have a look. There's another pair in my pocket—use those for yourself."

But if the Germans were there, they were concealing their presence with a good deal of care and skill.

"Have to go lower, then," decided Greene. "Get ready! We'll shoot the chutes now."

He pointed the monoplane straight down, cut out his motor, and glided earthward in a glorious volplane, the most wonderful sensation that even flight, with all its wonders, can afford. When the earth seemed about to come up and hit them, though it was still actually a good five hundred feet below, he caught the machine, righted it, and started the motor again. Then he had to fly back until he was again directly over the woods, and once more, while the monoplane moved very slowly, they peered down. But still there was no sign.

"Humph!" said Greene. "If they were supposed to be anything but Germans, I'd say you'd told us a cock and bull story, young 'un! English troops, or French, would show some sort of a light. Some fool would take a chance to get a smoke. But these Germans! They're not men—they're machines. They'll obey orders that officers wouldn't take the trouble to give in any other army. We'll have to make sure. Up we go again!"

Frank could not see how going up would make it possible for them to get the information that coming down hadn't afforded. But he said nothing, because he had come to feel by this time that when Captain Greene did a thing he had a perfectly sound reason for his action. Nor was he wrong. Once more they climbed in a high spiral curve until they were higher than they had been before. For the first time, Frank now felt a peculiar ringing in his ears. He mentioned it, and Greene laughed.

"Pressure," he said. "You'll get used to it! Lord, sometimes I've felt as if my head would burst when I started to climb. But it doesn't last long. Feel in the seat there beside you, at your left. There ought to be a big electric torch."

"Here it is! I've got it, sir," said Frank, a moment later.

"All right. Touch the button at the end. Let's see if it lights up properly."

It did, decidedly, for the result was a blinding glare.

"Pretty powerful, isn't it?" said Greene. "It's used for signalling, you see. Flash the light, and you can reproduce Morse perfectly. When you're high up it can be seen a long way, too. Now hold it straight down and flash it, then give a steady glare. Let us see if we cannot draw anything."

Frank obeyed, at the same time getting a glimpse of Greene's idea. He held the torch pointing straight down, and saw the beam of light shooting straight down. It was not powerful enough, of course, by the time it reached the treetops, to illuminate them, and so make anything below visible, but it was certainly strong enough to be observed from below, he thought. But still there was no movement, and the uncanny silence and darkness below persisted.

"All right. There's still another chance," said Greene, patiently. He drew a revolver from his pocket.

"Flash your little light this way. Let me see if it's all right," he said.

Frank obeyed.

"New fangled automatic—very powerful, and shoots a .44 bullet almost as far as an old-fashioned rifle," explained Greene. "Very useful if one runs into another 'plane unexpectedly—and the other fellow happens to be a German."

A moment later he opened fire, shooting straight downward. He could not aim, of course, but it was not his object to hit anything. He emptied one clip of cartridges, and before the last shot was fired the woods below began to spit fire. At once the monoplane began racing.

"Got 'em!" cried Greene, exultingly. "I thought that would do it! It isn't human nature to be under fire without sending back a shot or two—not even German human nature!"

No bullets came near them, but there was no longer any possible doubt that the Germans were below. The fusillade had settled that. Greene slowed down.

"Show your light quickly, then douse it at once," he cried.

Frank flashed the light of the big torch for an instant. And at once the monoplane shot forward.

"See the point?" cried Greene. "They'll aim at where the light was. Only we won't be obliging enough to be there! Well, this is a good night's work, my lad! You were right, and if I'm not much mistaken, you'll get your name in dispatches for this. The beggars! I'd like to know how they got through without being spotted!"

All the time the monoplane was racing away. But suddenly there was a sharp crack behind them, and in an agony of concern Greene twisted around in his seat.

"Oh, Lord!" he groaned. "I crowed too soon! That's the petrol tank—bullet hole! It'll leak out, and we can't stop the leak!"

"If you went down right away, would it all get out before you reached the ground?"

"No, but they'll catch us if we go down here. Can't do that."

"It's the only chance!" said Frank. "Isn't it?"

"You're right. I'll take it. Good boy! You don't mind the risk?"

"No!" said Frank.

Then they were rushing down. It was a desperate venture. Greene pointed for a field, but in the darkness the risk of capture by the Germans was the least that they faced.

Greene had cut out his engine; there was too much danger of an explosion, with the leaking petrol, to allow the spark to continue. He had to volplane down this time, not as a quick way of descending, but as the only means of preventing a disastrous fall. Even in broad daylight there is always risk in landing with a dead motor. Here, in the darkness and with unknown country below, the risk was multiplied a hundred times.

All that Greene knew with any certainty was that he was over country broken up into fields. The fences were numerous, there were ditches, too, and obstructions of all sorts. The larger ones he could see readily enough, when he got close; it was the smaller ones that threatened the real danger.

But if the danger was great, Greene was a master of his craft. He swooped downward. Then, when he was scarcely a hundred feet up, he caught the machine with a fine show of skill and held it, for a moment, on an even keel.

"We'll chance it in the next field," he called. "Can't stay up any further. Here goes!"

Down, down, they went. Then they were down, bumping along. But the element of luck that, despite all his skill, Greene had to have, favored him. The field was smooth and the monoplane came to rest safely. In an instant both were out, Greene first, since Frank, having to free himself from his straps, was delayed.

"Quick! The small flashlight!" called the flyer. "Here, give it to me! If we're to save any essence we've got to be quick!"

He took the light. But a quick look over the tank failed to show a spurting stream of gasoline.

"By Jove! Wonder if I could have been mistaken? Perhaps it was something else they hit!" cried Greene. But then he groaned. As he unscrewed the cap of the tank and peered in, he saw that it was bone dry.



CHAPTER XIII

A DANGEROUS ERRAND

For a moment Greene was speechless with despair. Fate had tricked him, it seemed, after he had done his best—and a better best than most men could even have attempted. Then he grinned.

"We'll have to hoof it," he said. "A good twelve miles, too! If we were champions at cross-country work it would take us the best part of two hours. And it's so long since I've used my legs that I don't know how long I'll be."

"There's one chance," said Frank. "I remember that I saw a little inn on the road the Germans took this afternoon. We're not so very far from that now. These little inns along the roads in France all have petrol for motorists who run short. If I went there I might get some."

Greene shook his head doubtfully.

"The government's taken all the essence it could find," he said, "I don't believe they'd have any. And, besides, there's a good chance that the Germans have men there."

"Still it's a chance," said Frank. "Won't you let me try? If I can't get it we shan't lose much time. And if I do, look at the difference it would make."

"That's true enough," said Greene. "All right, try it. I'll mend up the hole, when I find it, and if you do get some essence, we can be off at once. Good luck!"

Frank was on his way already, slipping away in the direction whence they had come. Luckily enough, he got his bearings by the windmill from which he had observed the wood into which the Germans had gone. To make his way to the road along which he and Henri had first seen the Germans passing was an easy matter. But he was afraid of roads by this time, and the more so because he knew that the Germans, having been aroused by the attack from the sky, would be doubly on the alert. So he stuck to the side of the road, religiously taking advantage of every bit of cover he could find to escape the foe.

"They knew they'd given themselves away just as soon as they fired at us," he reasoned, thinking half aloud as he trudged along, which was a habit of his. "And I don't believe they know they hit us at all. They do know that they didn't bring us down at once. Anyhow, there's no reason for them to be secret any more, and if they stay in that wood, they'll throw out pickets now, because they'll think that as soon as we went back and made our report troops would be sent to rout them out. It's up to me to be mighty careful."

That was good sound reasoning, too. From all he had learned since the war began, he knew that the Germans were by no means foes to be despised. They had been pretty generally victorious, but that was not all. They had shown a capacity for being always ready, for thinking of everything that might come up to block their plans. And he was sure, therefore, that the German commander would not argue that the aeroplane had got clean away just because the probabilities indicated that it had. He was almost certain to beat the country within a reasonable area for it, in the hope of finding it crippled and thus unable to carry the news it had come to get.

"I bet the Germans wouldn't have sent just one aeroplane," he reflected. "They'd have sent two, so that if anything happened to one, the other could have brought back the news."

But though he was thinking hard, he didn't linger as he went. Soon he came to the transverse road along which the Germans had gone, and turned in the direction they had taken. It was beginning to rain a little now, and it was very dark. He still stuck to the fields, though he was close to the road, and he found nothing to bar his way to the inn. When he got there, moreover, he found the place dark and deserted. Not a soul was in sight, but there were evidences that spoke as eloquently as men or women could have done. In the tap room furniture was smashed and broken and shattered glass was about the floor. Plainly the Germans had stopped as they went by.

"Of course!" he said, to himself. "If there were people here they took them along with them. They wouldn't be likely to leave any French people, whose first idea would be to tell what they had seen! It's certainly lucky that they didn't see us. We'd be with them now, I guess."

It was spooky work exploring the abandoned inn in the damp, dark night and with the knowledge that German soldiers were probably no great distance away. It was less than a quarter of a mile to the edge of the wood that had assumed such an important aspect, and he expected at any moment to hear the footsteps of intruders. None the less he went about his task quietly and coolly.

"If they had any essence, they'd hide it," he said to himself. "They'd know that both armies would need it for automobiles and aeroplanes, and they'd try to keep any they had left. So it won't be in any of the usual places."

For that reason he did not even leave the main building to make a search in the stable that was used as a garage. Instead, he went into the cellar. Here it was still plainer that the Germans had passed through. His feet stepped into puddles of sticky dampness, and, using his flashlight, he saw that it was wine. The heads of casks had been knocked in; broken bottles, too, strewed the floor.

This, however, had not been wanton destruction, he was sure. It had an object, and that object had been to prevent the soldiers from getting anything to drink. Troops on an errand requiring such extraordinary secrecy as had been maintained in this case could not be allowed to drink any liquor. That would have spoiled in all likelihood the remarkable discipline of which Captain Greene had spoken.

But, once more, it was not his business to think of what he saw, or to speculate about it, but to find the petrol if any was to be found. And he stumbled upon the hidden store quite suddenly, and quite literally, too. In one corner of the cellar was what looked like a pile of kindling wood. Harry kicked it indifferently in passing, and was almost thrown when his feet encountered a resistance more solid than he had any reason to expect. He looked down, and there, under the kindling, were two ten-gallon cans of petrol!

"I knew it must be there!" he cried to himself. He was down on his knees in a moment, shaking the cans to make sure that they were full. One had never been broached; the other was nearly half full. And this second can was the one he took. That would be more than enough to get the monoplane back to headquarters, and there was no reason for burdening himself with too great a load. He picked up the can, and at the same moment his heart leaped up into his throat, for overhead there came the sound of heavy footsteps. For a moment he stood as if paralyzed, listening.

The footsteps continued; guttural voices sounded,—the voices of Germans. It was impossible to distinguish what they were saying; and it made no difference, in any case. The only point that mattered was that they were there; that they blocked the only means Frank had of getting away with the precious petrol he had so luckily found.

He was safe enough personally. Even if they were led to come down into the cellar the chances were all in favor of his being able to conceal himself. What he feared was that some use was to be made of the place, and that the men whose voices he heard would stay there, thus preventing him from getting out of the building and so getting the petrol to Greene. It was more than possible, he thought, that the German commander, knowing that the presence of his troops in the woods had been discovered, would decide to use this place for headquarters.

And what he could hear confirmed this idea. There was a continual tramping overhead. Men came and went. That seemed to indicate that the occupation was to be permanent. He racked his brains for some means of escape. Windows there were none in the cellar. He found no trace of a trap door, such as there would have been in almost any American cellar. And then the saving thought came to him like a flash. He debated for a moment, then decided that the risk was worth taking. First he took his can of gasoline to the steps. Then he poured a little into a broken bottle, and poured this, in turn, on the wood under which he had found the cans. He dragged the full can of petrol to the other side of the cellar. And then, very deliberately, he set a match to the gasoline soaked wood and retreated to the steps.

The fire he had started blazed up at once, owing to the petrol. And at once a thick, acrid smoke filled the place. He was well up on the stairs, and thus safe from being choked. But he was in danger should the Germans come down, though even so, since the steps were wide, there was a chance for him. But he did not expect them to come down. He thought the smoke would drive them out, since as nearly as he could judge his fire was directly under the room in which the most of the commotion upstairs was taking place.

It was not long before he heard coughing upstairs, the first sign that the smoke was doing its work. By that time a brisk fire was burning. It had run up the posts to the beams that formed the chief support of the room above, and to his delight Frank saw that these burned far more fiercely and quickly than he had hoped. Plainly the wood was old and dry.

Above, as the fire spread, louder cries succeeded the coughing. And then came the crucial test by which his daring experiment had to stand or fall. Some one opened the door at the head of the stairs. Now, if ever, he was to be discovered! But as the door was opened the smoke was drawn up, and the German who had come to it jumped back.

"The whole place is burning! Get out!" he cried, in German. "There may be explosive spirits still down there!"

He slammed the door shut, and Frank heard running footsteps above. He waited until there were no more, and then, almost overcome by the smoke, slipped through the door. No one was left in the hallway into which he came. The place was full of smoke. He did not venture to the front door by which he had entered, but, still dragging his can of petrol, went to the back. Going through the kitchen, he found another door, as he had been sure he would and in a moment he was drinking in the cool, fresh air. The rain that was beating down on him now was welcome.

Just as he reached the open there was a sharp explosion behind him, and he looked back, to see the windows on the ground floor glowing. That was the other can of petrol, as he could guess readily enough. At once he ducked, and, running low, got well to one side of the house. Then, just as a great burst of flame lighted up the whole scene, he dropped to the ground, and lay peering toward the road in front of the inn.

A dozen officers and as many men, all in the German uniform, with the spiked helmets that made them so unmistakable, were in the road, staring at the burning house. And it was not until Frank saw how angry one of the officers was that he realized what a useful idea his had really been. Now detection of the Germans was certain. Investigation was almost certain to be made of a fire in a building so far out of the range of the German artillery as this. And so, even if neither he nor Captain Greene got back in time, the torch he had lighted, meaning only to secure his own escape, was likely to prove a death blow to the German hopes of secrecy.

Frank could not hear what the Germans were saying, but he had no intention of getting closer in an attempt to do so. Instead, having satisfied himself that there were no pickets behind the burning inn, he began crawling cautiously to the rear. It was a difficult task, especially so because of the petrol, which was no light burden. But he managed to get well out of the lighted zone and then he decided that it would be safe to straighten up and walk along.

As he went along the burning building served him well. It gave him a fixed landmark from which he could lay his course to the spot where he had left the monoplane and Captain Greene. By looking back from time to time he could correct his course, when he was crossing fields. And so without the guidance of roads, and partly to make better time and partly to avoid stray German pickets, he chose to stay away almost entirely from the roads and go across country.

From the fields in which they had descended to the inn the distance, as nearly as he had been able to guess it, was about a mile. He shortened this somewhat on the return trip. And he was within a quarter of a mile of the meeting place when he became suddenly conscious of something that was not just right. At first he was tempted to stop, but he overcame the temptation. The thing that had warned him of a possible danger was a trifling noise, yet one that was out of the ordinary. What the noise was he could scarcely have told. Perhaps the breaking of a twig, perhaps the slipping of a foot along a suddenly encountered patch of mud. At any rate he was sure that he had been followed.

He slowed down and now he could hear, or thought he could, the heavy breathing of at least two men. He was not certain of this; he was willing to admit to himself that he might be fancying it.

"If they're after me, why don't they take me?" he wondered to himself. But the explanation came to him almost as soon as he had asked himself the question. Whoever was following him could reason from the sight of the can of petrol he was carrying that he was going to some definite place where that petrol was wanted. And it would require no great stretch of the imagination for his trailers to decide that he must be carrying fuel to the aeroplane that had worked such havoc with the German plans.

"They think I'll lead them to the 'plane," he thought. Half a dozen plans for misleading them came to him. But none seemed practicable. Frank was intensely dogged in his determination to accomplish anything he had set out to do. The idea of giving up now, even to mislead his pursuers and so save Captain Greene from capture, was repugnant to him. He wanted to foil the men behind him—unless, as was possible, he only imagined that they were behind him—and still do what he had set out to do, which was in this instance to refill that empty petrol tank on the monoplane.

It was the purely accidental movement of putting his hand into his pocket to dry it off that gave him the idea. It met the pocket flashlight Captain Greene had given him, and at once he remembered a use for it of which the aviator had told him. To follow the plan did not mean that it would succeed, but it represented a chance, anyhow. And so when he came to the fence which he remembered climbing on his way from the monoplane, he stopped on the top rail, having pushed his can of petrol through first. In the field now immediately in front of him, but far away still, on the other side of the field, lay the monoplane. He could not see it in the driving rain but he knew that it was there.

There too would be Greene, waiting for him, and in all probability at this moment straining his eyes watching for his return. On that depended his chance of success in the plan that had come to him. On that, and on Greene's presence of mind and quick-wittedness.

So, still astride of the top rail, he began signalling with his pocket flashlight. He spelled out his message in Morse code, using a long pressure of the releasing switch for the dash and a short one for the dot. Word by word he spelled out his message, telling that he suspected that at least two Germans were trailing him. And at the end he signalled a request that if he had understood, Greene should wait a half minute and then imitate an owl's cry. He chose an owl because he had heard one or two earlier in the night. And he added that if he got the signal he would keep on heading for the monoplane. He suggested nothing to Greene; the rest was decidedly up to the aviator. Frank had done his share.

If there were Germans actually within sight of him, they did not attempt to interfere with him while he was flashing his message. But he had reckoned confidently that they would not. He was sure that he had not betrayed the fact that he knew he was being followed, and they would naturally suppose that this stop for signalling was part of a pre-arranged plan. He now dropped to the ground, picked up his can and took two or three quick steps. Then he stopped abruptly and was sure that he heard a footstep behind him. He grinned to himself, and just then the hoot of an owl sounded. Then he went on.

"I'll make it easier for them," he said. "Perhaps they wouldn't like to follow me right across the field!"

So he skirted the fence and the hedge at the side, and went around three sides of the field to reach the monoplane. And, as soon as it was in sight, all his suspicions were verified, for from behind there came a sharp exclamation in German, and he was told to stop, just as a heavy hand gripped his shoulder.

"Ja, we were right!" exclaimed one man in German. "There is their aeroplane! Now for the other—"

He never finished the sentence. Instead, he threw up his hands and pitched forward, just as a revolver cracked sharply in the silent night. With an oath the man who held Frank threw him aside, at the same moment shooting in the direction of the flash of Greene's pistol. But the Englishman's revolver spoke at the same moment, and he too fell. Frank's ruse had saved the day!



CHAPTER XIV

MENTIONED IN DISPATCHES!

"Keep back!" called Greene sharply to Frank.

His revolver still in his hand, he flashed the powerful light Frank had used in the monoplane into the faces of the two Germans. They lay groaning within a foot or two of one another.

"No tricks!" said Greene, sharply. "I don't want to finish you, but I'll shoot again if you make a move, except you can throw away your revolvers."

He spoke in German, and both of the wounded men obeyed. Frank was immensely relieved. He had been afraid that they had been killed, and the thought had sickened him. He realized fully that it would have been in accordance with the idea of war had Greene killed them both; that it would have been no more than his duty. And yet he was more than glad that they were alive and, so far as he could judge at that moment, not badly hurt or not dangerously wounded, at least.

"Fill that tank with the petrol," said Greene to Frank, "but leave a little in the can."

Frank obeyed, wondering why the order was given. Then Greene pushed the monoplane along the ground for some distance until it was in a favorable position to take the air.

"All right! Get in!" he said. "Strap yourself in. Know how the straps go? Right! I'm going to make a bonfire. It'll bring someone to help those poor chaps. I don't want them to have to lie here all night unless they have to."

He took the can which Frank had almost emptied and poured what gasoline remained on the ground that had been protected from the rain by one wing of the monoplane. Then he flung a match into the now highly inflammable stubble, and a flame leaped up at once, lighting the monoplane and the two wounded Germans. In a moment more he was in his place and the monoplane was plunging along the ground. Then it took the air and rose swiftly to a safe height. And then for the first time there was a chance for explanations.

"By Jove, how did you come to think of flashing that message to me?" cried Greene. "That was an idea! I almost gave it all away by answering before I realized what you were telling me. What was that fire I saw? Looked to me like the very place you said you were going to."

So Frank explained.

"Oh, splendid—my word, splendid!" cried Greene. "I fancy we'll find they've started this way already. Hullo—yes, by Jove, there come some of our fellows now! See, over there to the right? Aeroplanes—gone to spot those Johnnies. They didn't wait for us to come back!"

He dropped to a bare hundred feet of elevation now and in a moment Frank could see why. Below them a mass of cavalry was in motion.

"There they go!" cried Greene. "Your beacon gave them the line. The general must have decided that was confirmation enough."

Now came a shouting from below, and Greene answered it by swooping down to a landing in the field. An officer put his horse to the wall and rode up beside them.

"Captain Greene, by any chance?" he called, peering at them.

"Yes, colonel," said Greene, saluting. "The Germans are in a clump of woods on the Amiens road. In an angle of that road and the one from LaFere, rather. I don't know the exact strength, but have reason to believe about five thousand."

"There's no doubt about their being there, though?"

"None at all, sir. They shot a hole in my tank, and I had to wait to get enough essence to come back. All mine leaked before I could make a landing to plug the bullet hole. Did you start on the sight of that burning house?"

"Yes. The staff couldn't see why a house should be burning unless there were Germans about. Very well. Report back to headquarters, captain. They're waiting for you."

"Very well, sir."

"I thought so," he said to Frank, when they were in the air again. "You'll hear more of this night's work before you've done, my boy. There's a deal of gratitude due you. But I'd like to know what those Dutchmen were up to!"

Five minutes more saw them landed safely at headquarters, and it was only a few moments before they were in the presence of General Smith-Derrien. He listened to Greene's brief report in silence.

"There is more to be told of what my passenger and observer did, sir," he added, when he had sketched the essential facts. "I will make a written report of that direct to you."

"Do so," said the general. "You have done very well. Had it not been for the information we have obtained in this way, the whole headquarters staff might have been captured. The Germans evidently learned, through spies, of the orders that had been issued for continuing the retirement, and had slipped this force through to intercept the staff. I have been able to turn the tables on them, however. They will have trouble, I think, in escaping the forces sent against them."

For some time heavy firing had been heard in the direction of the woods where the Germans had lain. Now this died away. General Smith-Derrien glanced significantly at a colonel of his staff and permitted himself the luxury of a smile, a rare one for him in those days of the retreat.

Just then the telephone on his table rang. The nearest officer answered, listening attentively for a moment.

"Colonel Mewbray using the field telephone, sir," he said to the general. "It's been connected with our wires here. He reports that the horse artillery completely surrounded the wood in which the Germans were quartered, and shelled the woods for ten minutes. After that the Germans ceased firing, and when we played searchlights a dozen white flags were shown. The German commander, General von Garnst, surrendered to avoid a further useless sacrifice of lives."

The general nodded.

"My compliments to Colonel Mewbray," he said. "Ask him to convey my thanks to Brigadier-General Lannin. The German prisoners will be placed on trains at once and sent to Paris, through Amiens. The staff will prepare at once to take the new position as indicated in the order of to-night. Orderly!"

"Yes, sir!" said a private, stepping forward.

"My motor is to be ready in five minutes."

"Yes, sir."

The orderly went to transmit the order. Then the general turned to Frank and held out his hand.

"I shall see to it that you and your companion Boy Scout are mentioned in dispatches," he said. "I shall also see to it that your scoutmaster is informed of your excellent work, and shall request him to give you the highest possible promotion for distinguished services!"



CHAPTER XV

THE RETREAT

Frank felt that he was dismissed, and a gentle pressure on his arm from Captain Greene made him sure of it. The aviator went out with him, and when they were outside he slapped him on the back.

"Well, you've got a right to feel proud of yourself!" he said. "And the general doesn't begin to know all you did. He will, though, as soon as he gets my report. I'll write that directly because there's no telling what will happen any time I go up. You've seen something of how it goes in a monoplane."

"I wonder what I'm to do now," said Frank.

"Go away from here as quickly as you can," said Greene, with a laugh. "I can tell you that much. That's what we've been doing ever since they smashed us at Mons, in Belgium. You see those beggars creep out, trying to get around us. The Frenchmen made a bad guess at the beginning, and sent too many men to Alsace, and so this chap Von Kluck had enough men to threaten to surround us. But his turn's coming!"

"When?" asked Frank.

"Ask me something easy! Before very long, though, I think. We'll be south of Amiens by to-morrow. We've got to wait until we get enough men. But there's a surprise coming to the Germans. If I told you any more I'd be shot at daybreak for betraying military secrets. Good luck, young 'un! Sorry you're not going to be with us in the flying corps!"

"Good-bye," said Frank.

Then he went to look for Henri, and found him in the same room in which they had first been received by Major Cooper. Henri started up with a cry of delight at seeing him and embraced him, in the French fashion, to the huge amusement of the Englishmen present and Frank's own disgust and embarrassment. But he tried to hide how he felt, for he knew that Henri was only doing what he had been brought up to regard as the proper thing, and he would not have hurt his chum's feelings for the world.

"You two youngsters have got to get back to Amiens," said the major. "For one thing because the Germans will be here as soon as we get out, and for another because I want you to take some dispatches to the French staff there. Can either of you drive a motor?"

"I can," said Henri, proudly.

"Really? All right. I'd rather not spare a man. You will take these dispatches in the same containers in which they were brought, and deliver them to Colonel Menier, if he is still in Amiens. If not, to Major Fremille. You will also turn over the motor car to the French authorities there. Shall you stay in Amiens after that, even if the French leave, which they will?"

"Yes, sir, unless there is something we can do elsewhere."

"I rather think you'll be able to do more there than anywhere else, if the Germans don't drive you out. But you'll hear of that from the French officer you report to. By the way, when I spoke of the convoy that resisted a Uhlan attack, you didn't tell me you'd had anything to do with that. Why not?"

"We didn't, sir," said Frank, surprised. "We got away just as the fighting began."

"Yes, and sorry to go, too, I'll wager! Captain Hardy reported that it was your quickness and intelligence that saved him, and enabled him to get help up in time to save the convoy. Something about the hands of a clock you saw moving, eh?"

"That was nothing, sir," said Frank. "I just happened to see that they'd moved, when a minute before the clock had seemed to have stopped."

"Maybe it was nothing, but we hadn't got on to it before. And if they've been doing that at all steadily it accounts for the way they've been able to drop shells on to what we supposed were concealed positions. They shelled the house the staff was in two days ago. We're giving them a good fight, but they beat us pretty badly when it comes to spying. If we had a few more people with eyes as quick as yours, we'd be better off. Come on, I'll take you out and see you started."

As they reached the street they saw General Smith-Derrien climbing into a great automobile that started off at once, moving south toward Paris. What little they had seen of him had already made them conceive a great admiration for the silent British commander, who only a few days later was to be honored as the first brilliant figure of the war on the allied side. It was for his very conduct of this retreat that Field Marshal French, the British commander-in-chief, selected him for special mention in his dispatches.

They had to wait a few minutes while Major Cooper attended to the details of getting a car for them.

"Oh, Frank," said Henri, wistfully, "I wish I'd been the one to go! Though I wouldn't have done so well, I'm sure of that."

"Nonsense! You'd have done as well, and better," said Frank.

"No! But think of what you have done for France, for what is done for the English now is done for France as well. I am glad the English are fighting with us now, instead of against us. I—"

Major Cooper's return interrupted him.

"Here's your car coming now," he said. "You'll have to take a long way around. There are troops, or will be, on all the direct roads, and, besides, bridges are being blown up fast. Take the road that leads to Abbeville, over toward the sea. Use your own judgment about when you turn south, but keep moving toward the west until you are very close to Abbeville. After that you will have a fairly clear course. We haven't any reason to think that the Germans are in that direction at all as yet, though where they may be to-morrow no one knows. I needn't tell you to keep your eyes open. But if you do run into Germans, don't try to get away. There's very little chance of their finding the papers you carry, and, if they do, it is not important enough for us to want you to run any great risk. If you see them coming, hide at once. The motor doesn't matter."

Henri took the driver's seat and Frank sprang in beside him. And Henri, feeling that he had been pushed a little into the background, started the motor at once. He really could drive a car, having learned from his father years before, and he soon showed, when he had made himself familiar with the details of his machine, that he was to be trusted with it. And so, with a blast of his horn, he made a quick turn and sent the car roaring into the night. That was only to show off, however, for in a moment he muffled his engine, and the car spun along almost in silence, the motor purring evenly, as if to show that it was in perfect trim and ready to give the car all the speed that was needed.

The rain had stopped by this time, but the roads were still muddy and greasy, and at first, too, there was a good deal of traffic. Guns and men were moving, and, moreover, there was another danger. The German guns had evidently moved up, and a shell fell near them once in a while, but not so near as to bother them.

After a few miles of travelling, however, they found the road freer, and found also that the sound of the rear guard engagement that was covering the British retreat was further off. Five miles saw them riding through fields where twinkling lights showed the presence of troops, and they were stopped by a French guard. The pass Major Cooper had given them got them through, and the soldiers laughed and chatted while an officer was examining it. These were fresh troops, hurriedly brought up to hold off the Germans while the exhausted British retired to new positions, and they were gay, light-hearted fellows. True, they had not yet been in action, but to Frank it seemed that they were likely to be jovial after they had heard bullets singing over their heads.

"They don't seem to feel bad," said Henri. "And it is the same with the English. They are retreating, and still they are cheerful."

"You say that as if it was something remarkable!" said Frank, with a laugh. "Of course they're cheerful. They've got faith in their leaders, and they know, I suppose, that a retreat is often necessary. They'll turn the tables before long."

"It seems strange to be where it is so quiet," said Frank, when they had finally passed beyond sound of the skirmishing on the extreme left of the allied line, formed by the French force through which they had passed. "I'm expecting to see Germans every time we make a turn."

"So am I," said Henri. "And why shouldn't we? If they are trying to turn the allied flank, we're as likely to see them in this direction as not."

"Look here," said Frank, "you're perfectly right. We haven't got orders to make particularly good time. Let's keep on right to Abbeville. That's at the mouth of the Somme. Then we can turn toward Boulogne. If there are Germans around here at all they'll be in that direction. We might get some trace of their cavalry. Or we might do what we did before, strike some of their infantry. I don't think we're so likely to do that, though."

"We'll try it, anyhow," said Henri.

And so they turned toward St. Pol, instead of making the sharp turn at right angles that would have brought them to Amiens. Here there were traces, indeed, of a German invasion. Peasants, alarmed by the reports of Uhlans seen at Arras and near Boulogne, were in full flight.

"We needn't bother about that," said Frank. "Anything that these people know the intelligence department has found out. No troops advancing at all openly could get by the aeroplanes without being seen. And I think the railroad in this direction has been watched. I saw a lot of aeroplanes flying over this way this afternoon, and there would be more from Boulogne. There are English warships there, I've heard, and their naval flyers would cover this part of the country."

Suddenly Henri slowed down the car. He kept one hand on the wheel, the car moving slowly forward, but his gaze was fixed on the sky. Finally he stopped the car altogether.

"Look up there," he said, quietly, to Frank. "Do you see that light? First I thought it was a star. But there aren't any other stars, and now I'm sure it's moving. Do you see?"

He pointed, and Frank's eyes followed his finger.

"You're right," he said. "Hello! Now it's gone—no, there it is again! See, it flashes and then disappears! It's some sort of a signal from the air. Keep the car still."

He tried to follow the flashes of the light, hoping to read the message if it was in Morse code. But he soon found that it was not. And then Henri cried out sharply.

"If it's a signal, it's being answered from over there!" he said. "See, there's a light waving there. It looks as if it might be from the roof of a house. I—"



CHAPTER XVI

A DARING EXPLOIT

Frank leaped out.

"Turn the car around first," he said. Henri obeyed. "Now try your starter. Cut out the motor and then see if she starts quickly."

Henri, mystified, obeyed.

"Why?" he asked.

"Because when we want to start, we may have to do it in an awful hurry," said Frank. He searched the road for a moment. "Run her back a few feet to where that big tree is. It's darker there than anywhere else around here. All right, that's far enough. We'll have to take the chance of something coming along while we're gone and bumping into her but I don't believe there's much risk of that. Now, come on! And quiet! We've got to get up to that place without being seen."

Cautiously they approached the house. No lights showed in any of its windows; the place looked deserted. Indeed, all around it were traces of hasty flight. It was a wayside inn, of a type common always in France, commoner than ever since the spread of the craze for automobiles and motor touring. Suddenly Frank stopped.

"Wait a minute for me," he said. "I've got to go back to the car. I ought to have thought of it before."

"What do you want?"

"Batteries. I saw a coil of wire in the car and I want that, too. And there must be batteries. A car like this would carry everything needed for small repairs, wouldn't it?"

"Yes. I think you'll find them under my seat."

Frank was back in less than five minutes.

"All right," he said. "I don't know whether we'll have time to do what I want or not, and whether I'll be able to do it, anyhow. But it's worth trying. Now come on past the house. Easy! This is the hardest part of it."

They slipped by. However, Frank uttered a suppressed exclamation as soon as they had done so. Before them, on the right of the road was a field easily two or three times as large as the ordinary French field. As a rule the land in France is split up into very small sections, closely cultivated. But here was a cleared field as large as those commonly seen in England or America, with no fences for perhaps a quarter of a mile in any direction. Henri turned to look back at the inn.

"They're still signalling from there—and look! There are two lights now, instead of one, above!"

These lights were still some distance away. Frank studied them. Then he led the way into the field.

"I thought so!" he said, with suppressed triumph in his voice. "Do you see those barrels over there toward the inn? There's petrol in those—or I'll eat my shirt!"

"And if there is?" said Henri. "What then?"

"Can't you guess? What do you suppose those lights mean?"

"Aeroplanes?"

"Never! They wouldn't flash that way. They'd have to be in a different position entirely. No. Dirigibles!"

"Zeppelins?"

"Perhaps. Perhaps Parsevals or Schutte-Lanz airships. I think Parsevals, for they need gasoline. And Zeppelins could fly from Brussels or Liege, almost from Cologne—oh, I have it! That's why they need petrol!"

"Why?"

"They haven't flown over Belgium at all! They are from the sea!"

"Oh—so that they could come secretly, and not be seen as they passed over Belgium?"

"Yes. If they flew over Belgium they would have to cross some territory that the Germans do not hold, and word would go to Antwerp and from there to the army here. Now quickly! They will be here soon. They are coming nearer every minute."

They went to the barrels as fast as they dared. There was nearly a score of them, all close together. Each had a tap, and it was proof enough that they contained petrol to open the tap of one. The smell identified them beyond any doubt whatever.

"Come on, and help me dig a hole," said Frank. He dropped to his knees, and began scooping out the soft earth with his hands. Henri fell to with a will, though he was sadly puzzled. But when the hole had been dug to a depth of perhaps two feet, and Frank began to hollow out a trench toward the barrels he began to understand. And as soon as he did, he worked as hard as Frank himself, careless of torn finger nails and bleeding hands. They carried the trench to the foot of one of the barrels, and Frank turned the tap. The gasoline ran out into the trench, and flowed to the hole. Frank ran back to the hole.

"Stop it when I give the word," he said. "Now!"

Then he was busy with the copper wire he had brought from the automobile for several minutes. The wire had been carried either to repair cut telegraph or telephone wires, or to serve as the conductor for a field system of lighting. But whatever its original purpose had been, Frank was thankful now that he had found it. He worked fast, and was satisfied at last.

"Now a little straw and a few twigs over the hole and the trench—and the sooner they come, the better!"

"Yes, the sooner, the better!" echoed Henri, tremendously excited, now that he understood, even if rather vaguely, what Frank planned. "Vive la France! A bas les Allemands!"

As they went back toward the road Frank trailed the wire behind him in two lengths. And when they reached the road, he dropped into the ditch, and was busy for some minutes.

"Now if it only works!" he said. "Perhaps it will; perhaps it won't. But it can't do any harm. That's certain."

"They're coming closer. I think I can see their shapes now—and there are two of them," said Henri. "Do you see?"

For a moment Frank could not. Henri's eyes were sharper than his. But then he did make out vaguely two immense shapes that were coming through the air. Soon, too, the faint hum of their powerful motors made itself heard.

"Zeppelins and big fellows, too," said Frank. "All the better!"

He wondered if his plan would work, and if he would be able to carry it out. If, in the final test, would he dare to do what he had tried to arrange? Time enough to think of that when the moment for decision came. And meanwhile there were a hundred things that might happen to ruin his plan. There was nothing to do now but wait. But every moment of waiting brought the climax nearer. The hum of the motors of the airships rose louder on the quiet air, broken only by the faint and distant mutter of the battle that was still being fought miles away. It sounded now like the buzzing of a swarm of bees, magnified a thousand times. And then the field was full of men, rushing from the inn. He wondered how they could have been concealed there. But such wonder was idle, and he did not think of it. Instead he watched keenly. First one monstrous aerial battleship came to rest on the earth. At once the men in the field surrounded her, seizing the ropes that were flung out, and made her fast.

There was a good deal of noise. Men were calling in German of course. But soon order was restored, and the only voices were those giving commands. Suddenly Frank's face lighted up.

"Did you understand, Henri?" he said. "The men in the field are to be the crews for the fighting. They have sailed here with only enough men to steer them. And now all are ordered out, to stretch their legs!"

"Yes, I heard that order," said Henri.

"Now keep your eyes glued to them. What are they doing?"

They listened and watched intently.

"Just as I thought," said Frank. "See, they are going to fill the tanks. There, they are attaching hose. And they have a pump—they surely must have a pump, to send the petrol uphill!"

Meanwhile the other airship had come down, on the other side of the barrels, and there as nearly as they could judge, the same procedure was carried out.

"Watch, Henri! Are they pumping?" cried Frank.

"Yes!" said Henri. "Now—now—now is your time, Francois!"

Frank hesitated the fraction of a second.

"If it meant killing them, I could not do it," he said, solemnly. "But they are all out of the airships. Now!"

On the word he closed the circuit he had made by connecting the loose ends of the wire he had carried from his petrol filled hole to the two batteries he had brought from the car. He had broken the circuit at the other end, leaving the two wires separated by the fraction of an inch, and cunningly held in place. The result was a spark—or would be, if he had not erred.

And he had made no mistake! For as he closed the circuit, he saw a flash of flame at the spot where he and Henri had dug the hole into which the petrol had flowed from the barrel they had opened. The spark had fired the explosive gas that results when petrol is mixed with air. The flame ran along the shallow trench, and, amid a chorus of shrieks from the Germans who scattered in all directions, the fire reached the barrel. In a moment there was a loud explosion. The flame flew to the other barrels—the whole neighborhood of the barrels, owing to the mixture of the petrol and the air, was then filled with an explosive and inflammable gas.

There was a great flash of flame, broken by a dozen sharp reports as one barrel after another blew up.

And still, though the Germans were flying in all directions, plainly visible in the light of the blazing gasoline, the real success of Frank's plan hung in the balance. But then what he had calculated happened. The flame ran through the lines of hose. And a moment later two great shafts of flame marked the spread of the fire to the helpless monsters of the air. There was no chance to save them. Indeed, even the Germans had no other thought than to save their own lives. Their raid, whatever its ultimate object, was ruined and two vessels of the great air fleet of the Kaiser were destroyed.

For a moment after the final catastrophe the two scouts stayed, caught by the wonder and the magnificence of the ruin they had wrought. But then Frank cried out,

"Come on! We haven't a moment to lose! They'll know that that was no accident! Some came running this way. They'll find the wires! And then they'll know. The wires will bring them here. Hurry!"

They began running desperately toward the automobile.



CHAPTER XVII

THE ESCAPE

Their one chance of escape, as they both realized fully, was to get back to their automobile before the Germans recovered themselves sufficiently to begin searching for those who had brought such swift and terrible disaster upon their enterprise. And so they made no effort to move quietly or secretly now. To do so would have meant delay and delay was what they could not afford. The distance seemed far greater than when they had first traversed it. It seemed that they would never pass the house which the Germans had used as a base. But finally they reached it. And as they did so a door burst open, and they saw a light within.

A man, with the cap of a German officer, though otherwise he wore civilian clothes, came rushing out, tugging at his pistol. He had heard them running. By some bad chance, then, there had been a man—a German—left in the inn!

"Stop!" he cried, furiously.

But they kept on running. He could not see them, dazzled as he was by coming from the lighted house into the deep darkness of the road. But he was in front of them, and they slowed up, instinctively, though they still ran. And then they came into the light of the door. He started back.

"Kinder!" he cried. "Children!"

It was the exclamation of the Uhlan who had stopped them in the afternoon. But now it was uttered in a vastly different tone. The German was beside himself with rage. Perhaps he had had some heavy share of responsibility for the safety of the Zeppelins. But whether that were so or not, he was plainly maddened by the sight of the boys. He could scarcely have understood how completely they were responsible, but the way they were running and the direction whence they came proved only too clearly that they had had some hand in it.

"Stop, Henri!" cried Frank, suddenly. "We can't get away. We surrender!"

They stopped. Frank was obeying the order Major Cooper had given him. Perhaps, had he been alone, he would have risked a further attempt to escape. But there was no doubt that the German meant to shoot, and he could not expose Henri to the risk.

They stopped full in the path of light that came from the open door of the inn. Behind them, in the road, voices were raised. It was plain that their wires had been followed, and that others were in pursuit. And, after all, Frank felt they could afford to grin at being made prisoners now. They had accomplished a great feat. Even if they were caught, that was to their credit.

And then suddenly he gave a cry of horror. Henri was a little ahead of him for he had not been able to stop as abruptly as Frank. And the German officer, too furious, perhaps, to think of what he was doing, raised his pistol and fired point-blank at the French boy! He fired—but there came from his pistol not a sharp report, but only the dull click as the hammer fell. Twice more he pulled the trigger. But something was wrong. He had made a fatal error—his revolver was unloaded.

But it was only by the luckiest of accidents that Henri was still alive. Frank had seen the murderous attempt, and now rage mastered him for the moment.

"You coward!" he shrieked. He flung himself at the German officer, who was trying frantically to get at his cartridges. So sudden was the attack that he was taken utterly by surprise. Before he could defend himself, Frank was wrenching his arm. A moment more, and the German officer squealed like a frightened pig, for Frank had succeeded in getting a hammer lock on him. He pulled at the revolver with his other hand, and at last the German, to escape a broken arm, had to loosen his grip. Even a weakling can cripple the strongest man if he once gets that hold. And Frank, in his rage at the cowardly thing he had seen, was almost a match for the full grown man in any case.

As soon as he got the revolver he let go of the German's arm. But before the officer could move, Frank had clubbed the pistol and struck him sharply on the head. He went down like a log.

"Run, Henri, run!" he cried. "They're coming up behind us! Run for the car!"

Behind them, indeed, the footsteps of running men were plainly to be heard. A shot rang out, but both boys had turned instinctively to the side of the road and were running low in the ditch beside the highway. They could not be seen, and the firing ceased. It seemed that most of the men were unarmed, or carried revolvers at the most. Had there been rifles behind them, they would have had no chance. But as it was, they reached their car and leaped in. Henri threw the switch of the electric starter, the motor leaped into throbbing life, and they were off.

Behind them more shots were fired, but the aim was wild. And they sped away, at fifty miles an hour, pursued only by a few vain revolver bullets, and by a chorus of shouts and yells of rage and execration.

"The coward!" stormed Frank. He had never been so angry in his life. "He might have killed you, Harry! And just because he was in a rage over what had happened to the airships! He didn't even know that you'd had anything to do with it—not positively! And we'd already surrendered."

Henri laughed—and he meant the laugh. It was not affectation. He had faced his danger in the true spirit of the Frenchman, who is as brave in action as any man in the world.

"Eh, well!" he said. "He did not shoot me, so what does it matter? That was a fine crack on the head you gave him! He will remember us, I think, next time he sees us."

Frank shuddered a little.

"I hope not!" he said. "Or, that if he does, he will be a prisoner himself, and won't be able to try to get even."

Frank remembered the look of sheer devilish rage in the eyes of the German. It was not pleasant to think that they might meet again.

"If it is to be, it will be," said Henri. "I bear him no grudge! He had cause to be angry—ma foi, yes! The Kaiser will not say pretty things when he hears of what we did to-night, Francois!"

"No!" Frank laughed. "I wonder where those airships were meant to go? Paris? They could have done terrible damage. Perhaps they were to attack the army—to lie behind its course, knowing that our aeroplanes would be scouting on the front. They might have made it harder than ever to retreat in good order. But I think they would have gone to Paris. I think that they would have been there before daylight."

"And now—pouf!" said Henri. "What is left of them? Not so much as would fill a barrel!"

Once all danger of pursuit was past, Henri had slowed down the speed of the car. Both scouts were thoroughly tired out by this time. They had had a strenuous day, and a night that merited the description of strenuous even more fully than the day. And now that danger seemed to lie behind them, and a clear road to safety in front, their weariness was realized fully for the first time.

They could hardly have escaped the Germans, had any lain between Abbeville and Amiens. But none were there, as it turned out. The road was clear and open before them, and the car rolled along smoothly.

"The firing seems to be moving now—moving to the southeast," said Henri, once.

"I think our left wing is being drawn in a little. That will tighten up the line. But it gives the Germans still more chance to get around the wing."

"We can bring up French troops to meet them, Frank. There is the garrison of Paris—nearly five hundred thousand men. They have not struck a blow yet. But if the Germans come too near, they will be brought up to the first line."

"I believe that's what the French plan is, Harry!" said Frank. "Yes, why not? To lead the Germans on and then take the risk of leaving Paris defended only by its forts, and try a new flanking movement of their own. Do you see? A new army, which could outflank the Germans while they thought they were outflanking us!"