smack, which caused Chester to
stagger back.

At that moment Hal leaped upon the German from behind. His right fist
struck the man a stunning blow on the back of the neck. The German
wheeled and clinched with his opponent, and for a moment they stood, arms
locked about each other, swaying upright in the boat.

Then Hal, putting forth every ounce of his strength, succeeded in
breaking his opponent's hold, and gave him a violent push. The German
staggered and tottered; but, in the very act of falling overboard, his
outstretched hand grasped Hal by the collar and both tumbled into the
river together.

Chester scrambled to his feet as the two pitched into the river. As they
went over the side, violently tipping the boat, it suddenly turned
turtle. Chester went flying through the air and disappeared beneath the
water with a loud splash.

Still locked in each other's embrace Hal and his opponent rose to the
surface. Both had one arm free and struck out blindly at the other's
face. Hal landed two short-arm blows, and the German sent one home.
Neither had an advantage, however, and they sank again.

At almost the same instant Chester's head appeared above the water. He
cast a quick look around, but could see no sign of the other two
occupants of the boat. Treading water, he remained close to the spot
where the water bubbled up. Two or three seconds later the heads of the
struggling pair again appeared above the water.

Chester acted promptly. Swimming rapidly up to them, he raised his right
arm and sent his fist crashing full into the German's face. The latter's
already white countenance turned whiter, and gradually his hold on Hal
relaxed. With a quick movement Hal freed himself, and the German sank
from sight.

Without waiting to see whether he would come up again both lads struck
out for the opposite shore.

But they were too late.

When the little motorboat had capsized, four French soldiers had run down
to the bank and thrown themselves into the stream. Almost at the same
time a squad of perhaps a dozen Germans had performed the same maneuver.
Now, from both sides of the river, men were closing in upon the almost
exhausted lads.

But the Germans were the best swimmers and overtook them first. One
grasped Hal by the arm and another seized Chester. In vain did the lads
try to shake off these opponents, striking out blindly at them, and
calling to the French to hurry to their assistance.

In spite of the superi