Before undertaking their kindly though dangerous mission, Tom and Jack had carefully studied it from all angles. At first Jack had been frankly skeptical, and he said as much to his chum.

“You'll never get over the place where Harry is held a prisoner,” declared Jack. “And, if you do, and start to dropping packages, they'll never land within a mile of the place you intend, and Harry'll have the joy of seeing some fat German eat his chocolate cake.”

“Well, maybe,” Tom had agreed, “But I'm going to try.”

To this end they had secured the best map possible of the ground in and around the prison camp. Its location they knew from the dropped glove of the aviator, which contained a note telling about Leroy.

It was not uncommon for Germany to disclose to her enemies the names of prisons where certain of the Allies were confined, and this was also done by England and France. The prison camps were located far enough behind the defense lines to make it impossible for them to be reached in the course of ordinary fighting.

Then, too, the airmen of Germany seemed a step above her other fighters in that they were more chivalrous. So Tom and Jack felt reasonably certain as to Leroy's whereabouts. Of course it was possible that he had been moved since the note was written, but on this point they would have to take a chance.

To this end they had provided themselves not only with the best maps obtainable showing the character of the ground and the nature of the defenses around the prison, where Harry and other Allied men were held, but inquiries had also been made by those in authority, at the request of Tom and Jack, of German prisoners, and from them had come information of value about the place.

Of course the two air service boys had no hope of inflicting much damage on batteries or works outside the prison. By the dropping of some bombs they carried they hoped to distract attention from themselves long enough to drop the packages to Leroy. The bombs were a sort of feint.

And now they were on their way, winging a path over their own lines, and soon they would be above those of the Hun.

Some of the former comrades of Tom and Jack, having been apprised of what the lads were to attempt, had, without waiting for official orders, decided to do what they could to help. This took the form of a daring challenge to the German airmen to come out and give battle.

After their thorough drubbing of the day before, however, the Boche aviators did not seem much inclined to venture forth for another cloud fight. But the French and some English fliers who were acting with them, laid a sort of trap, which, in a way, aided the two Americans.

A half dozen swift Spads took the air soon after Tom and Jack ascended, but instead of flying over the German lines they went in the opposite direction, making their way to the west. They got out of sight, and then mounted to a great height.

Shortly after this some heavy, double-seated planes set out for the German territory as though to make observations or take photographs. It was the belief of the French airmen that the Huns would swarm out to attack these planes, or else to give battle to the machine in which Tom and Jack rode. And, in such an event, the swift Spads would swoop down out of a great height and engage in the conflict.

And that is exactly what occurred. Torn and Jack had flown only a little way over the trenches of the enemy when they saw some Hun planes coming up to meet them. It was in the minds of both lads that they were in for a fight, but before they had a chance to sight their guns, some French planes of the slow type appeared in their rear.

To these the Huns at once turned their attention, and then the Spads swooped down, and there was a sharp engagement in the air, which ultimately resulted in victory for the Allied forces, though two of the French fliers were wounded.

But the feint had its effect, and attention was drawn away from Tom and Jack, who flew on toward the prison camp.

Had their mission been solely to carry words of cheer with some material comforts to Harry Leroy, it is doubtful if Tom and Jack would have received permission to make the trip. But it was known they were both daring aviators and good observers, and it was this latter ability on their part which counted in their favor. For it was thought they might bring back information concerning matters well back of the German front lines, information which would be of service to the Allies.

And in furtherance of this scheme Jack and Tom made maps of the country over which they were flying. They had been provided with materials for this before leaving.

On and on they flew, changing their height occasionally, and, when they were fired at, which was the case not infrequently, they “zoomed” to escape the flying shrapnel.

But on the whole, they fared very well, and in a comparatively short time they found themselves over the country where, on the maps, was marked the location of Harry Leroy's prison camp.

“There it is!” suddenly exclaimed Tom, but of course Jack could not hear him. However, a punch in Jack's back served the same purpose, and he took his eyes from his instruments long enough to look down. Then a confirmatory glance at the map made him agree with Tom. The air service boys were directly over the prison camp.

This, like so many other dreary places set up by the Germans, consisted of a number of shacks, in barrack fashion, with a central parade, or exercise ground. About it all was a barbed wire stockade and, though the character of these wires did not show, there were also some carrying a deadly electric current.

This was to discourage escapes on the part of prisoners, and it succeeded only too well.

But the camp was in plain sight, and in the central space could be seen a number of ant-like figures which the boys knew were prisoners.

Whether one of them was Leroy or not, they were unable to say.

But they had reached their objective, and now it was time to act. High time, indeed, for below them batteries began sending up shells which burst uncomfortably close to them. They were of all varieties, from plain shrapnel to “flaming onions” and “woolly bears,” the latter a most unpleasant object to meet in mid-air.

For the Germans were taking no chances. They knew the vulnerable points of their prison camp lay above, and they had provided a ring of anti-aircraft guns to take care of any Allied, machines that might fly over the place. Whether any such daring scheme had been tried before or not, Tom and Jack could not say.

Of course it was out of the question that any great damage could be done in the vicinity of the camp without endangering the inmates, so it was not thought, in all likelihood, that any very heavy air raids would have to be repelled. But in any case, the Huns were ready for whatever might happen.

“Better drop the bombs, hadn't we?” cried Jack to Tom, as he slowed down the motor a moment to enable his voice to be heard.

“I guess so—yes. Drop 'em and then shoot over the camp again and let the packages fall. It's getting pretty hot here.”

And indeed it was. Guns were shooting at the two daring air service boys from all sides of the camp.

In the camp itself great excitement prevailed, for the prisoners knew, now, that it was some of their friends flying above them.

There was another danger, too. Not many miles away from the prison camp was a German aerodrome, and scenes of activity could now be noticed there. The Huns were getting ready to send up a machine—perhaps more than one—to attack Tom and Jack.

It was, then, high time they acted, and as Jack again started the engine, he guided the machine over a spot where the anti-aircraft guns were most active.

“There's a battery there I may put out of business,” he argued.

Flying fast, Jack was soon over the spot, or, rather, not so much over it, as in range of it. For when an aeroplane drops a bomb on a given objective, it does not do so when directly above, but just before it reaches it. The momentum of the plane, going at great speed, carries any object dropped from it forward. It is as when a mail pouch is thrown from a swiftly moving express train or a bundle of newspapers is tossed off. In both instances the man in the train tosses the pouch or his bundle before his car gets to the station platform, and the momentum does the rest.

It was that way with the bomb Jack released by a touch of his foot on the lever in the cockpit of the machine. Down it darted, and, wheeling sharply after he had let it go, the lad saw a great puff of smoke hovering directly over the spot where, but a moment before, Hun gums had been belching at him.

“Good! A sure hit!” cried Tom, but he alone heard his own words. Jack's ears were filled with the throb of the motor. He had two more bombs, and these were quickly dropped at different points on German territory outside the camp.

At the time, aside from the evidences they saw, Jack and Tom were not aware of the damage they inflicted, but later they learned it was considerable and effective. However, they guessed that they had created enough of a diversion to try now to deliver the packages containing the letters and other comforts.

Jack swung the machine at a sharp angle over the prison camp, and as he cleared the barbed wire fence Tom, who had been given charge of the packets, let one go. It fell just outside the barrier, caused by some freak of the wind perhaps, and the lad could not keep back a sigh of dismay. One of the three precious packages had fallen short of the mark, and would doubtless be picked up by some German guard.

But Tom had the satisfaction of seeing the two other bundles fall fairly within the prison fence, and there was a rush on the part of the unfortunate men to pick them up.

“I only hope Harry's there,” mused Tom. “That's tough luck to wish a man, I know,” he reflected, “but I mean I hope he gets the letters and things.”

However, he and Jack had done all that lay in their power to make this possible, and it was now time to get back to their own lines if they could. The place was getting too dangerous for them.

Swinging about in a big circle, and noting that groups of prisoners were now gathered about the place where the packets had fallen, Jack sent the machine toward that part of France where they had spent so many strenuous days.

“They're going to make it lively for us!” cried Jack, as he noted two swift German planes mounting into the air. “It's going to be a fight.”

But he and Tom were ready for this. Their Lewis and Vickers guns were in position, and they only awaited the approach of the nearest Hun plane to unlimber them. They mounted steadily upward to get beyond the range of the anti-aircraft batteries and were soon in comparative safety, since the Huns, at this particular sector at least, were notoriously bad marksmen.

With the German planes, that would be a different story, and Tom and Jack soon found this out to their cost.

For one of the Boche machines came on speedily, and much more quickly than the boys had believed possible was within range. The German machine guns—for it was a double plane—began spitting fire and bullets at them. They replied, but did not seem to inflict much damage.

Suddenly Tom saw Jack give a jump, as though in an agony of pain, and then the young pilot crumpled up in his seat.

“Badly hit!” exclaimed Tom with a pang at his own heart. “Poor Jack is out of it!”

The machine, out of control for a moment, started to go into a nose dive, but Tom let go the lever of his machine gun, and took charge of the craft, since it was one capable of dual manipulation. Tom now had to become the pilot and gunner, too, and he had yet a long way to go to reach his own lines, while Jack was huddled, before him, either dead or badly wounded.