The boys sat up and rubbed their eyes sleepily.  Outside it was light.  The gray dawn crept through the entrance, dispelling the shadows of the darkened hut.

“What was it?” cried Chester.

And, even as he spoke, it came again, the heavy boom of a single huge cannon, followed almost immediately by the crash of thousands upon thousands of rifles.  The machine and rapid-fire guns broke loose with their leaden messengers of death, and a bugle sounded: 

“To arms!”

CHAPTER XVIII.

The battle.

Captain Derevaux, who had been sleeping soundly, sprang to his feet, picked up his sword and pistols, and, without even a word to Hal and Chester, dashed from the hut.

“The battle has begun!” cried Hal.

“Come!” exclaimed Chester.  “Let’s get to some place where we can see.  I can’t stay here!”

“Nor I!” cried Hal.  “Come on!”

The two lads hurried from the hut.  As they emerged, a troop of Belgian cavalry swept past them, on the way to the front.  The boys followed as rapidly as possible in its wake.  Presently they came to a small hill.  Climbing to the top, they found they could command a good view of the advancing German columns, which they could see in the distance, and which were even now almost close enough to grapple hand-to-hand with the horsemen swooping down on them.

All along the German front the Belgian cavalry hurled itself upon the advancing foe.  They met with a crash, and horses and riders went down in heaps.  For a moment the Germans gave way.  For a moment they recoiled, and then they sprang forward again.

The charge of the Belgian cavalry was magnificent, but it was in vain.  The German forces pressed onward, and the cavalry was forced back, cutting and slashing as it slowly retreated.  Under a withering fire, that suddenly broke out all along the German front, the horsemen fell by hundreds.  It was more than flesh and blood could stand.  A retreat was sounded, and the cavalry fell back upon its support.  But, even as they drew off, there burst from the German front the sharp roar of the mitrailleuse.  The German maxims had opened fire.  The Belgians fell faster than before.

And now the Germans were ordered to charge.  Squadron upon squadron raced over the open ground in a mad dash toward the Belgian line; and as they charged, the rapid-fire guns of the great forts poured forth their answer.  Great holes were cut in the German columns, and men and horses were mowed down like chaff.

And still the Germans came on.

Suddenly a fierce rifle fire broke out all along the Belgian front, even as the rapid-firers continued to belch forth their messengers of death.  Men reeled and fell in masses.  The Germans wavered, halted, then retreated.  A great shout went up from the Belgian lines.

Under the support of their own field batteries, the Germans reformed for a second charge.  As before, the defenders waited until they were close, then poured in a deadly fire.  The Germans staggered, then sprang forward.  A second volley greeted them, and a second time the Germans wavered, halted and retreated.  A third time they charged, with the same result.