ir-raided before, or they wouldn't have the
anti guns ready. The most likely place to find the best cyclone cellars
will be near the officers' headquarters, I think. Trust those fellows to
have a safe place ready."

"Do you think they are making the raid to help us?" asked Joe.

"Hardly," replied Blake. "They probably don't even know that we have
been captured. No, I guess this has been in preparation on our side for
some time, judging by the number of craft in it. I hope they wipe out
this dump!"

"But not until we get under cover!" said Joe. "Look! There goes one of
our ships!"

As he spoke a white cloud seemed to burst in the vicinity of one of the
aircraft. The machine, which with the others had come lower down, was
seen to dip and plunge. Then, after what seemed a dizzy fall, it
straightened out again and kept up with the others.

"Hit but not disabled," murmured Blake, as he and his chums paused in
their race for shelter. "The Germans are getting the range, I guess."

"Why don't we drop some bombs?" cried Joe, speaking as though he and his
friends were personally engaged.

"I guess they're waiting until they get in a favorable position,"
returned Blake. "Look out! Here comes one!"

Something black dropped from one of the airships. It fell in a long
curve, landing in a spot which the boys could not see, and an instant
later there was a terrific explosion.

"That hit an ammunition dump, all right!" cried Charlie. "Duck,
fellows!"

"In here!" yelled Blake, for at that moment they came opposite what
looked like the entrance to a tunnel. It was lighted by small electric
lamps and appeared to extend some distance into the earth. No one could
be seen in it or entering it as the boys made a dive for it.

And it was well that Blake, Joe and their assistant found shelter when
they did, for an instant later the whole area was under bombardment by
the airships. The boys, racing through the tunnel, dug underground and
timbered and braced as is a mine shaft, could not see what went on, but
they could hear and imagine.

By this time the American and French aeroplanes were directly over the
German camp and were dropping tons of explosives. The bombs struck and
burst, some of them setting off stores of ammunition and powerful powder
designed for the big guns. And these explosions, combined with the
firing of the weapons aimed to bring down the flying enemy, made a
pandemonium which penetrated even to the tunnel alon