Finally came the welcome signal that announced the arrival of the last of the air fleet. All was now ready for the start. Every pilot knew what place he was expected to occupy in the formation; and when another flash was seen they took up their positions.
The leader occupied the place of honor. After him came two more planes a little apart. The next pair were even further away from each other, and so it went on to the end. In as far as Jack could make out, the expedition at its start very much resembled the formation seen when a flock of wild geese passes overhead, winging its flight toward the South in the fall or toward Canada in the spring, making a triangle, or spear head, with an old gander at the apex in supreme command.
Later on, as occasion arose, this formation would be changed, the battleplanes surrounding the heavier bombers in order to protect them from any hostile attack.
Far below could be seen occasional lights. These they knew came from some camp of the Huns, where the tired soldiers were sleeping in anticipation of another hard day's work ahead. Off to the right a fire was burning, perhaps some building in the process of destruction to prevent its falling into the hands of the Americans, who were in line to overwhelm it on their next day's drive.
These things, however, received very little attention from the raiders. They were more interested in the possibility of their progress being halted by some block of Hun machines, bent on breaking up the raid before it was well started.
No doubt, information had leaked concerning the assembling of all these latest model planes. There were always ways whereby clever and daring spies could communicate with their mates on the other side of the fighting line, which was the main reason for so much secrecy in planning this particular expedition.
So most of the time both Tom and Jack kept their eyes fixed on the line ahead, waiting eagerly for the signal to close in.
"There she goes!" called out Jack suddenly; but of course his companion had already seen the signal light from the leading plane, and was commencing to carry out his part of the programme.
Enemy planes had been discovered barring their further progress, quite a squadron of them being in the air, with others rising as they caught the sound of the bustling motors coming from the south.
This was the first crisis in the raid. The Huns were "out for blood," as Jack termed it, and would do their utmost to break up the formation. Their object would be to confuse the Yankee pilots, and thus weaken the force to the extent of making them abandon their plan.