This hill was of particular importance to the Germans, for it commanded the approach on all sides; and now the German Prince had determined upon its capture.  General Petain anticipated the move and acted promptly.

It was toward this point, then, that Hal and Chester found themselves moving upon the sixth day of the great battle.  They bore despatches from General Petain and each bestrode a high-powered motorcycle, which the French commander had placed at their disposal.  The two lads rode swiftly, for there was no time to be lost.

Even above the “pop-pop” of their motorcycles could be heard the terrible roar of the German guns as they were brought to bear on Dead Man’s Hill, paving the way for an infantry advance, which was to come a few hours later.  It was risky business upon which the lads were bent, for the great shells struck on all sides of them, throwing huge masses of dirt in the air like giant fountains and digging immense excavations in the hard ground.

But the lads reached their destination in safety; and here, for the first time, Hal and Chester were to come in contact with a new method of fighting.

General Domont, in command at Dead Man’s Hill, having read the despatches the lads carried, announced that they would remain with him during the day, acting as members of his staff.  He ordered Hal forward with instructions for the troops holding the crest of the hill to the north and Chester was despatched upon a similar mission to the south.

Hardly had Chester delivered his message when a shout told him the German infantry was advancing to the attack.  The lad glanced around, and as he did so, a sharp order rang out and a moment later the French troops clamped queer-looking devices over their faces and heads.

Chester knew what they were—­gas masks to protect the defenders from the poisonous vapors of German gas bombs, which, had the defenders not been protected by masks, would have killed them instantly.  A passing officer said something unintelligible to the lad as he passed and pointed to the ground.  Glancing down, the lad perceived a mask and then understood that the officer had meant for him to put it on.  Chester did so, though not without some difficulty, for he had trouble adjusting it.  But with his nostrils protected at last, Chester turned to watch the approach of the enemy.

The Germans came forward in a dense mass, despite the fearful execution worked in their ranks by the French guns.  In the lines of the defenders dropped huge bombs that sent up dense vapors—­the deadly gasses of the foe—­but they caused little harm, for the French were protected.  Now and then a man fell, however; perhaps he had failed to adjust his helmet properly, or perhaps it was not perfect.  But for the most part the gas bombs had little effect.

The first concerted attack of the German troops availed little; and after trying for half an hour to gain a foothold in the French lines they withdrew.  But a second attack followed a few moments later.  This also was beaten off.  A third attack, however, met with better success.