time to
working for the boys wearing the khaki, and braving death itself under
Old Glory.

The night had up to then been fairly quiet.

Tired after the day's fighting, both armies lay down to rest, looking
forward to a renewal of hostilities when another day dawned. Doubtless
the retreating Huns would utilize this time in preparing many more of
the machine-gun nests, each of which was calculated to hold up the
advancing Americans for a certain period.

As for the Americans trying to advance during the night, that was
utterly out of the question, since under those trees a pall lay that
might hide any number of deadly traps, into which they, in their
ignorance, would surely stumble.

The three Air Service boys were still standing chatting with the girl in
khaki, whom they knew very well, and sipping their lemonade when,
without warning, there broke out a terrible din. The ground under their
feet seemed to shake with the force of an explosion, which they realized
must be quite near at hand.

Another explosion immediately followed, and then still more in irregular
succession. The boys had learned by now to tell what such explosions
signified, so they looked at each other aghast, and Jack cried out:

"The Huns are making an air raid on our lines back here! They must be in
great force, too, with all those bombs dropping! Tom, didn't it strike
you those explosions came mostly from the quarter where our Red Cross
field hospital lies?"

Tom felt a cold chill, the same thought having gripped him.

CHAPTER IX

THE NIGHT RAID

"IT struck me," exclaimed Harry, amidst the Babel of sounds that had
broken out all around them, girls and soldiers chattering like magpies
in concert, "that most of the explosions came from over where our
hangars are strung out! Yes, there they start up gain! Boys, I tell you
it's a big raid on our aviation camp! Let's chase over there!"

They all seemed of one mind, for hardly had Harry shrilled this
proposition than the three of them bolted from the exit of the hut and
commenced a mad dash through the intervening woods, heading for the
opening utilized by the air squads for their canvas hangars. The
successive bursts of flame accompanying those frequent explosions
benefited them in one way, since they were enabled to see fairly well
and thus avoid pitfalls, although once or twice there was a grunt as a
member of the group struck some obstacle which he had not noticed soon
enough.