it simply knocked him stiff to see the
transports coming in loaded to the guards with American troops. And he
says the roads are fairly choked with doughboys moving this way.
They're coming like a swarm of locusts. And there's millions more
where they came from. Oh, Uncle Sam is awake now, all right, and don't
you forget it! And when he once gets started there's nothing on earth
can stop him."

"Right you are!" said Bart.

"We've won every war we've ever been in and it's got to be a habit,"
grinned Billy.

The old Thirty-seventh was stationed on the second line, or what is
called in military terms, "the line of resistance." In modern
fighting, when a heavy attack is expected the defending army is usually
arranged in three lines. The first is the advanced line, and this is
hardly expected to be held very long. Its chief aim is to hold back
the enemy for a while and weaken him as far as possible. Not many
troops are employed on this line nor many big guns. The chief reliance
is on rifle fire and machine guns, which are so placed as to deliver a
withering cross-fire and cut up the enemy divisions.

By the time the first line is driven back the defending army knows
where the enemy has chosen to strike and is ready for him on the second
line or "line of resistance." Here the battle is on in all its fury.
If here again the enemy advances, there is still a third line of
"battle positions." This is practically the last entrenched position
that the defenders have. If they are driven back from this into the
open country beyond, it becomes a serious thing for the retreating
army, as many of their big guns will have been lost, and their forces
are apt to be more or less disorganized, while the enemy is flushed
with the victory he has so far gained.

The cannonade kept on with increasing fury all through the early
morning.

"Heinie must have plenty of ammunition," remarked Frank. "He's
spending it freely."

"It beats anything we've been up against since we came to the front,"
observed Billy.

"It seems to be coming nearer and nearer all the time," said Bart. "I
guess this is going to be our busy day."

There was intense activity all through the lines. Orderlies galloped
from place to place with orders. Big motor cars rumbled up, loaded
with troops who were hastily placed in position. The big guns of the
Allied forces had opened up and were sending back shell for shell over
the enemy lines.

For over