only artillery covering a
rear guard action. I wish you'd remember, Harry, that a retreat may mean
mighty hard fighting. Not a rout--a retreat. It isn't easy for an army
to move backward. But it's been done by a good many armies that won
later."

"Well, come on! We're not getting any nearer to the English by stopping
here to talk."

"No. We'll be off again. That noise is getting nearer, Harry. Or louder,
anyhow. Perhaps that only means that more guns are going into action."

Somehow the nearness of the battle stimulated them. They found
themselves making better time, though they had certainly seemed to be
riding as fast as they could before. And all the time the sound of the
cannon in front of them grew louder, and the quality of the noise
gradually changed. Soon loud explosions began to be distinguishable amid
the general hum of battle, and, too, there was an overtone,--a sharper,
less steady noise.

"Rifle fire, I think, too," said Frank. "It's lighter than the sound of
the cannon, but it seems to be just about as steady. And to think that
that's going on, all the way from here to the Swiss border nearly!
They're fighting here and near Verdun, and in the Vosges mountains."

"Look over there," said Henri, suddenly. "Do you see? That looks like an
omnibus!"

"It is--one of the sort they use in London!" said Frank, in surprise.

The great, unwieldy vehicle came lumbering toward them. It rolled along
the road, raising a tremendous cloud of dust, and they could see that
behind it were many more. Just behind it, too, a man on a motorcycle
came suddenly into view. He was mounted on a high-powered machine, and
they could hear the roar of his motor as he came up to them.

"Halte!" he cried, in a broken French. "Arretez vous!"

They were off their machines in a moment, saluting, as he stopped his
motor and put one foot on the ground to steady his machine. He was
dressed in khaki, and both of them recognized his uniform as that of the
British forces.

"We speak English," said Frank.

"The deuce you do! That's good! Well, tell me how to get to Guise. We've
lost our blooming way, that's what we've done! And we've got supplies
for the troops."

"You're going the wrong way--straight to Amiens," said Henri. "The road
to Guise is back four miles, at least. Can you turn your 'buses here? We
will guide you. We are going that way."

"You are, are you?" said the English officer. He laughed, curtly. "I
doubt that, young fe