sounded
from the air above them several explosions, and with them was an
undercurrent of humming and droning as if from a million swarms of
bees.

"The Boche aeroplanes! They're right over us--a whole flock of 'em!"
cried Roger. "And they're dropping bombs on us!"

CHAPTER XVII

A BATTLE OF THE AIR

What Roger had said was only too true. The advance of the American
army had been halted, at least temporarily, by a sudden attack from
a large number of German aeroplanes. The Fokkers had arisen from far
enough back of the place where the American shells were falling to
escape them. And then they had sailed directly over the advancing
Americans, the center formation of the Huns' ships of the air being
almost directly over where our five heroes were now stationed in the
woods.

"Bombs! I should say so!" cried Jimmy, as one landed on the other edge
of the woods, and blew a great hole in the ground. "This is getting
too close for comfort!"

The German machines, having flown from the direction of their own
lines across the American front, dropping bombs that did great
execution, were now coming back again, to repeat the performance, it
was very evident.

"Why didn't we bring up some anti-aircraft guns?" demanded Bob,
as though some officer, immediately over him, had neglected this
precaution.

"Guess no one expected the Huns would try this trick," said Roger.
"It's a daring move, all right."

"And it's a dangerous one for us, too!" added Jimmy, grimly. "These
woods are a pretty good protection against shrapnel and machine-gun
fire, but they're absolutely useless when it comes to screening us
from aeroplane bombs. Of course we can hide from the sight of the
flying Huns, but they must know this wood is full of Americans, and
a bomb dropped anywhere among the trees will get some of us. It's
fierce!"

"You said it!" cried Franz. "Wow! That was a bad one!"

A bomb--one of the winged affairs that wrought such deadly havoc in
Paris and London--had fallen not one hundred feet from where the five
Brothers were crouching in the underbrush. The concussion jarred
them, and the force of the explosion uprooted several large trees that
injured a number of the command, while the bomb itself killed three in
dreadful fashion.

"Why don't our flying lads get after 'em?" demanded Franz. "Surely we
have some planes over here now--in fact, I know we have; though not
nearly enough. Where are they?"

Well might he ask that,