No matter which turned out to be the truth, it was not pleasant for Jack to believe he had become an object of hatred to some mysterious prowler, and that possibly other secret attempts on his life might be made from time to time.
That day passed, and another followed. There did not seem to be much stirring on either side of the line; but such a lull frequently proved the precursor of some gigantic battle, for which the armies were preparing.
Of course, when the wind and weather permitted, there was always plenty of excitement among the airplane escadrilles. All manner of little expeditions were organized and carried out.
Now it was an attempt to get above that string of "sausage" balloons used for observation purposes only, so that a few well-dropped bombs might play havoc among them.
As these were always defended by a force of fighting planes hovering above, all primed to give battle on the slightest provocation, the result of these forays was that a number of hotly-contested fights were "pulled off" high in air.
One pilot brought down another enemy, and increased his score a peg, always a matter of pride with a pilot of a fighting plane. And another of the escadrille had the honor of getting above those observation balloons before a couple of them could be hastily pulled down.
Two of his companions engaged the defending Teuton pilots, and fended them off purposely, in order to permit the raid. The selected man swooped down like a hawk, passed the Gotha guard, and managed to shoot his bomb downward with unerring aim. One of the balloons was seen to burst into flames, and the second must have met with a like fate, since it was perilously near at the time, though the dense smoke obscured everything.
All these things and more did Tom and Jack witness through their glasses as those two days passed. Tom especially was waiting to have his wish realized with as much calmness as he could summon.
"I think it will come to-night, Jack," he told his chum, on the second afternoon, as they prepared to return to their lodgings.
"Then you believe there's some big move on tap, and that to-morrow a battle will be commenced? And all for the possession of some old ruined fort, perhaps, that is now only a mass of crumpled masonry and debris!"