There was a great upward blast of air which rocked the machine in which sat the two aviators. There was a burst of smoke and flame beneath them, tongues of fire seeming to reach up as though to pull them down.

Then came a terrific explosion which almost deafened the boys, even though their ears were covered with the fur caps, and though their own engine made a pandemonium of sound.

The air was filled with flying debris--debris of the German guns and men. The bombs dropped by Tom and Jack had accomplished their mission.

The hara.s.sing battery was destroyed. The German guns were silenced.

CHAPTER XXV. THE RESCUE

Tom and Jack circled around slowly over the place where the German battery had been. It was now no more--it could work no more havoc to the American ranks. It did not need the wireless news to this effect, which the aviators sent back, to apprise the Allies of what had happened. They had seen the hara.s.sing guns blown up.

Now out swarmed the Americans, charging with savage yells over the place that had been such a hindrance to their advance. Tom and Jack had done their work well.

There was no need for the one to tell the other what was in his mind.

There were still two of the powerful bombs left, and there was but one thought on this matter. They must be used to blow up, if possible, the camp near the German prison. Doing that would create havoc and consternation enough, the air service boys thought, to drive the captors away, and enable Leroy and his fellow prisoners to be saved.

Jack punched Tom in the back and motioned for him to shut off the motor a moment so that talking would be possible. Tom did this, and Jack cried:

"Shall we take a chance?"

"Yes!" Tom answered in return.

Strictly speaking, having accomplished the mission they were sent out on, they should have returned to their base for orders. But the airmen were given more liberty of action and decision than any other branch of the Allied service.

"Go to it!" cried Jack, and once more Tom started the motor and headed the craft for the Hun prison.

Again the air service boys were hovering over the prison camp. They could now see that there was much more activity around it than there had been before the big battery was destroyed. The fight was coming closer, and the Germans evidently knew it. Whether they were trying to arrange to take their captives farther back, or merely seeking to escape themselves from a trap, was not then evident.

And, having reached a position where they could see below them what looked to be a concentration of German guns, perhaps to fire on any force that might advance against the prison. Jack let fall one of his two remaining bombs.

It swerved to one side, and though it exploded with great force, and created havoc and consternation among the Huns, it did not fall where it was intended. The second battery was still intact.

"My last shot!" grimly mused Jack, as he looked at the other bomb.

Tom maneuvered the aeroplane until he had it about where he thought Jack would want it. The latter pressed the releasing lever and the bomb descended. It was the most powerful of the lot, and when it struck and exploded it not only demolished the defensive battery, making a hole in the place where it had stood, but it tore down part of the prison fence, and made such destruction generally that the Germans were stunned.

Instantly, seeing that all had been accomplished that was possible, and noting that hovering around him were other Allied airmen who had agreed to help in the rescue, Tom sent his craft down. There was a burst of shrapnel around him and Jack, but though the latter was grazed by a bullet, neither was seriously hurt. A Hun plane darted down out of the sky to attack the bold Americans, but quickly it was engaged by a supporting Allied craft. However, the Hun was a good fighter, and won the battle against this antagonist. But when two other Allied planes closed in, that was the last of the enemy. He was sent crashing down to satisfy the vengeance in toll for the life of the birdman he had taken.

Now Tom and Jack could see that their plan had worked better than they had dared to hope. The boldness of the attack from the air, coupled with the advance of the American army, started a panic in the German ranks.

They began a retreat and the regiments near the prison camp were included in the rout.

By this time either some of the prisoners saw that there was a break in the cordon around them, or they realized that a great battle was putting their guards to flight, for some of them made a rush toward a side where there were no Germans, and succeeded in breaking out--no hard task since part of the fence was shattered by the explosion.

"Now's our chance," cried Tom, though of course Jack could not hear this. "Harry may be among that bunch, and we want to get him and any others we can save."

He started the aeroplane on its downward path, while Jack, guessing the object, got the machine gun ready for action, since there might be a squad of Germans ready to give battle on the ground.

Several other planes of the Allies, seeing what was going on, swooped to the aid of the two Americans, for there were no other of the Hun craft within sight now. All had been sent crashing down, or had drawn off.

On either side of the immediate sector which included the prison camp, the battle was still raging fiercely, mostly with success on the side of the Americans, though in places they suffered a temporary setback.

In the vicinity of the prison itself wild scenes were now being enacted.

The prisoners were beginning to rise in force, for they saw freedom looming before them. There were fights between them and the guards, and terrible happenings took place, for the guards were armed and the prisoners were not. But as fast as some of the Germans fell they were stripped of their guns and ammunition, and the weapons turned by the prisoners against their former captors.

All this while Tom and Jack were descending in their plane. As yet they were uncertain whether they were to be able to rescue Leroy or not. They could not distinguish him at that height, though from the enthusiastic manner in which several of the newly liberated ones waved at the on-coming aeroplanes, it would seem that they were of that arm of the service, and appreciated what was about to happen.

Nearer and nearer to the ground flew Tom and Jack. And then, to their horror, they saw that several Germans had set up two machine guns to rake the prison yard, which was still filled with excited captives. The Germans were determined that as few as possible of their late captives should find freedom.

Tom acted on the instant, by sending the plane in a different direction, to enable Jack to use his machine gun. And Jack understood this, for, with a shout of defiance, he turned his weapon on the closely packed Germans around their machine guns.

For a moment they stood and some even tried to swerve the guns about to shatter the dropping aeroplane. But Jack's fire was too fierce. He wiped out the nest, and this danger was averted.

A moment later Tom had the machine to earth, and it ran along the uneven and sh.e.l.l-torn ground, coming to a rest not far from what had been the outer fence of the prison camp. A group of Allied captives, newly freed, rushed forward. Tom and Jack, removing their goggles, looked eagerly for a sight of Harry Leroy. They did not see him, but they saw that which rejoiced them, and this was more aeroplanes coming to their aid, and also a column of infantry on the march across a distant valley. The stars and stripes were in the van, and at this the rescuers and the prisoners set up a cheer. It meant that the Germans were beaten at that point.

"Where's Harry Leroy? Is he among the prisoners?" cried Jack to several of the liberated ones who crowded around the machine. There would be no question now of trying to save some one, a rush by mounting to the air with him. The advance of the Americans and the Allies was sufficiently strong to hold the prison position wrested from the Germans.

"Was Harry Leroy among you?" asked Tom, of the joy-crazed prisoners.

Many were Americans, but there were French, Italian, Russian, Belgian and British among the motley throng.

Before any one could answer him there was a hoa.r.s.e shout, and from some place where they had been hiding a squad of German soldiers rushed at the group of recent prisoners about Tom and Jack. Their guns had bayonets fixed, and it was the evident purpose of the Huns to make one last rush on the prisoners near the aeroplane to kill as many as possible.

The Germans were a sufficiently strong force, and none of these prisoners was armed. They began to scatter and run for shelter, and Torn and Jack became aware that matters were not to be as easy as they had expected.

But fortunately the fixed machine gun on the aeroplane, which was near the pilot's seat, pointed straight at the oncoming Huns. With a cry Tom sprang to the c.o.c.kpit and quickly had the weapon spitting bullets at the foe. Then Jack saw his chance, and, climbing up to his seat, he swung his gun about so that it, too, raked the Germans.

They came on with the desperation and courage of despair, but the steady firing was at last too much for them. They broke and ran--what were left of them alive--in what was a veritable rout, and this ended the last danger for that immediate time and place.

Other aeroplanes dropped down to help consolidate the victory, and the explosion of some American sh.e.l.ls at a point beyond the prison camp told its own story. The artillery had moved up to keep pace with the advancing infantry. The big battle had been won by Pershing's men, and the air service boys had not only done their share, but they had been instrumental in delivering a number of prisoners.

As the last of the Germans fled and Tom and Jack leaned back, well nigh exhausted by the strain of the fighting, a voice cried:

"Good work, old scouts! I knew you'd come for me sooner or later. At least I hoped you would!"

They turned to see Harry Leroy walking slowly toward them.

Harry Leroy it was, but wounds, illness, and imprisonment had worked a terrible change in him. He was but the ghost of his former st.u.r.dy self.

Still it was their chum and the brother of Nellie Leroy, and Tom and Jack knew they had kept the promise made to the sister. They had effected the rescue which the offensive made possible.

"Hurray!" cried Tom. "It's really you then, old scout!"

"What's left of me--yes. Oh, but it's good to see the flag again!" and he pointed to the colors on the aeroplane and on the advancing banners of the infantry. "And it's good to see you again! I'd about given up, and so had most of us, when we heard the shooting and knew something was going on. But how did it happen? How did you get here, and how did you know I was here?"

"Go easy!" advised Tom with a grin. "One question at a time. Can you ride in our bus? If you can we'll take you back with us. The others will be taken care of soon, I fancy, for our boys will soon be in permanent occupation here. Will you come back with us?"