Besides, constant vigilance was the price of safety in other particulars.

With almost a dozen of their own planes speeding through s.p.a.ce, a false move on the part of a careless pilot was apt to bring about a collision that could have only one result.

Jack made a discovery just then that caused him to cry out.

"The signal, Tom! We are to drop down and give the bombers a better chance to get there. No matter what the cost, we've got to reach that bridge to-night!"

Already Tom was changing the course. They had begun to swing lower, each unit of the attacking squadron in its appointed place. A brief interval followed, and then came the bursting shrapnel again around them, while from several quarters close by hovering German planes commenced using their machine guns, to be answered by the challengers in like manner.

CHAPTER VII

THE BATTLE IN THE AIR

The din soon became general, one after another of the American planes joining in the battle. The German aircraft held off a little, fighting from afar, evidently thinking to accomplish their ends without taking too much risk. Had they boldly a.s.saulted, doubtless the result would have been much more disastrous to both sides.

The big bombers had but one object in view, which was to bomb the important target below. To drop an explosive on a certain spot had been the most important training of those aboard these craft. They had been carefully selected from the ranks of the many observers taking service in the aviation branch of the service; and great things were expected of them now.

The Huns had concentrated the glare of numerous searchlights on the hub of the squadron's activities, so that the speeding planes could be seen darting hither and thither like bats during an August evening, darting around some arc-light in the street.

The flash of the distant guns aboard the planes looked like faint fire-flies in action. No longer was the earth wrapped in darkness, for flares dropped by the bombers kept continually on fire. The bridge stood plainly out, and a keen eye, even without the aid of gla.s.ses, could distinguish the rush of terrorized German troopers trying to get clear of the danger zone before a well directed bomb struck home.

Jack, leaning from his seat, took all this in. He was keyed to the top-notch by what he saw and heard. Tame indeed did most other incidents of the past appear when compared with this most stupendous event.

"Wow!" burst from his lips, as a sudden brilliant flash below told that the first huge bomb had struck; but with all that racket going on around of course no ordinary human voice could have been heard.

He could see that it had not been a successful attempt, for the bomb struck the ground at some little distance away from the terminus of the structure spanning the river. However, it did considerable damage where it fell, and created no end of alarm among those who were near by.

As yet the Air Service Boys had not been engaged with any of the hostile planes, though most of the other Yankee pilots seemed to be having their hands full in meeting and repelling fierce attacks.

Both kept in readiness for work should their turn come, Tom manipulating the plane, and Jack working the rapid-fire gun which he had learned to handle so cleverly.

Strangely enough, Jack, as he looked, was reminded of a vast circus which he had once attended, and where tumblers, athletes, and trained animals were all performing in three rings at the same time. He had found it utterly impossible to watch everything that went on, and remembered complaining l.u.s.tily afterwards in consequence.

Now there were some eleven rings in all, besides what was taking place thousands of feet below, where the bombs had started to burst, tearing great gaps in the ground close to the bridge, and causing the water itself to gush upward like spouting geysers.

Lower still dropped the venturesome pilots guiding the destinies of the four huge bombers. What chances they were taking, bent only on succeeding in the important task to which they had been a.s.signed!

Jack knew he would never forget that dreadful crisis, no matter if he were allowed to live to the age of Methuselah; such an impression did it make upon his mind.

But their turn came at length, for in the dim light two big Gothas were discovered swinging in toward them as though bent on bringing about the destruction of the Yankee battleplane.

Jack forgot about what was taking place below, since all of his energies must now be directed toward beating off this double attack.

It had come to the point of self-preservation. The Hun airmen were playing a prearranged game of hunting in couples. While one made a feint at attacking, the other expected to take advantage of an exposure and inflict a fatal blow that would send the American aeroplane whirling to death.

Jack saw when the nearest plane opened fire. The spitting flame told him this, for it darted out like the fiery tongue of a serpent. He also realized that the bullets were cutting through s.p.a.ce all around them; and a splinter striking his arm announced the fuselage of the plane had already been struck, showing the gunner had their range.

Then Jack began work on his own account, not meaning to let the fight become one-sided. His duty was to pepper any of the enemy craft that came within range, regardless of consequences. To Tom must be left the entire running of the plane motor, as well as the maneuvering that would form a part of the affray.

Heedless of what was taking place around them, the two chums devoted their attention to the task of baffling the designs of their two foes.

Wonderfully well did Tom manage his aerial steed. They swung this way and that, dipped, rose, and cut corners in a dizzying fashion in the endeavor to confuse the aim of the Hun marksmen.

Once Jack experienced a sudden sinking in the region of his heart. There was a strange movement to the plane that made him fear the motor had been struck. He also missed the cheery hum at the same time, and felt a sickening sensation of falling.

But immediately he realized that Tom was only executing his pet drop, the nose-dive. One of the Huns followed them down, just as a hawk-might pursue its prey. When the American plane came out of the dive at the new level Jack saw that the Hun was closer than ever, and once again starting to bombard them.

At least they now had only a single adversary to deal with, which could be reckoned a point gained. Most of the fighting was going on above them, but Jack believed the bombers must be somewhere near by, possibly at a still lower level.

Again the maneuvering, or jockeying, for position commenced. In this air duel the pilot who knew his business best was going to come out ahead. It might be they were opposed by some celebrated German ace with a long list of victories to his credit, which would render their chances smaller.

Tom, however, seemed to be keeping up his end wonderfully well. The hissing missiles cut through the canvas of their wings, beat upon the side of the fuselage, and even nipped the Air Service Boys more than once as they stormed past. Neither of the boys knew whether they were seriously wounded or not; all they could do was to fight on and on, until something definite had been achieved on one side or the other.

Once Jack felt something blinding him, and putting up a hand discovered that it was wet; yet he was not conscious of having been struck in the head by a pa.s.sing bullet. Dashing his sleeve across his eyes he shut his jaws still tighter together, and continued to play his gun as the opportunity arose.

They were coming to closer quarters, and the issue of the battle, however dreadful the result, could not be much longer delayed, Jack knew.

Then it happened, coming like a flash of lightning from the storm cloud!

CHAPTER VIII

BOMBING THE BRIDGE

"Tom, we've done it!" Jack shrieked, when he saw the enemy Gotha plane take a sudden significant dip and flutter downward like a stricken bird.

Evidently a shot more fortunate than any that had preceded it had struck a vital part of the rival craft, putting the motor suddenly out of repair.

When he felt his plane begin to crumple up under him the Hun pilot had commenced to strive frantically to recover control. Jack, horror-stricken by what was happening, leaned over and watched his struggle, which he knew was well nigh hopeless from the beginning.

Still the German ace made a valiant effort to avoid his fate. He could be seen working madly to keep from overturning, but apparently his hour had struck, for the last Jack saw of the beaten Gotha it was turning topsy-turvy, falling like a shooting star attracted to the earth by the law of gravitation.

That affair being over, Jack, breathing hard, now allowed himself to pay some attention to what was going on in other quarters. At the same time he proceeded to introduce a fresh belt of cartridges into the hungry maw of the machine gun, in case they were forced into another engagement.

Above them the battle still raged, though of course Jack could not decide which side might be getting the better of it. His interest focused chiefly on the bombing machines, which he found were now far away, moving along in erratic courses as their pilots strove to get in exact position for a successful blowing up of the bridge.

Jack could count only three of them. Unless the fourth had wandered far afield it looked as though disaster had overtaken its crew. No matter, even such a catastrophe must not deter those remaining from seeking by every means in their power to reach their objective.

Even as he stared downward Jack saw another of those brilliant flashes that proclaimed the bursting of a bomb. He felt a sense of chagrin steal over him, because so far no explosive seemed to have succeeded in attaining the great end sought. The bridge still stood intact, if deserted, for he could catch glimpses of it when the smoke clouds were drifted aside by the night breeze.

Fires were now burning in several quarters, started undoubtedly by some of the bombs that had missed their intended objective. These lighted up the scene and gave it a weird, almost terrifying aspect as witnessed from far above.

All at once Jack saw some bulky object pa.s.s between their machine and the ground below. It must be the missing bomber, he concluded, though the realization of the fact made him thrill all over in admiration of the nerve of those who could accept such terrible chances.

Yes, despairing of getting in a telling blow at such a height, the reckless crew of the big Yankee plane had actually dropped down until they could not be more than a thousand feet from the earth.