lunder. They
had been well drilled in all the maneuvers connected with just such a
hurried ascent in numbers. Each plane had its regular orbit of action,
and must not overstep the bounds on penalty of the commander's
displeasure.

After mounting to the arranged height, the Air Service Boys found that it
was a very animated region, though fully a thousand feet from the earth's
surface. Almost a dozen planes in all were moving in a great circle,
their motors lazily droning, and the pilots ready to enter into squadron
formation on signal.

In fact, Tom and his chum were the last to arrive, which under the
circumstances was not to be wondered at.

"All on deck, I reckon," called out Jack, after he had taken a survey
about him. "There's the signal from the flagship, Tom. We've got to
keep the red lantern ahead of us and fall into line. There go the
bombers to the center, and our place you said was on the left, tailing
the whole bunch."

Like a well disciplined aerial navy they fell into place, each taking its
position as previously arranged. When the formation was made complete
another signal was given. This meant the advance was now to begin, and
the crossing of the German lines undertaken.

Unless there chanced to be some mistake made concerning the proper
altitude required, so as to clear all possible bombardment when over the
Hun lines, this might be accomplished without danger. So far as was
known, they had gauged the utmost capacity for reaching them possessed by
the German anti-aircraft guns, and Jack promised himself to jeer at the
futile efforts of these gunners to explode their shrapnel shells close to
the speeding armada.

Something must have been underrated, however; and, in fact, few plans
can be regarded as absolutely perfect. The advancing raiders were
passing over the enemy front when a furious bombardment suddenly burst
forth below.

Jack could see the spiteful flashes of the numerous guns, and while the
sound of the discharges came but faintly to his ears, to his
consternation, all around them, as well as above and below, came sharp
crackling noises, accompanied by bursts of dazzling light.

They were actually in the midst of a storm of bursting projectiles and in
immediate peril of having some damage done to their swift-flying planes
such as would spell ruin to the enterprise, perhaps bring instant death
to some of the fliers!

CHAPTER VI

STRIKING A BLOW FOR LIBERTY

"Climb, Tom! C