“Take a troop of cavalry,” came the command, “and make a reconnoissance of the northeast!”

Quickly two officers nearby sprang from their horses and offered them to the lads, for the latter had not yet had time to find steeds.  The lads sprang into the saddle, saluted their commander, and dashed away.  To the nearest cavalry force they hurried, where upon repeating General French’s order to the commander, they soon had a troop at their disposal.

A troop of cavalry is composed of one hundred men.  It is usually commanded by a captain.

Now it is very unusual for a commanding officer to have two lieutenants on his staff, as had General French in the persons of Hal and Chester; but the General had commissioned them as such on the spur of the moment, and when they took command of the troop they consequently, for the time, superseded the captain in command—­for they were the personal representatives of the General himself.

The two lads placed themselves at the head of the troop and rode forward at a rapid trot.  Past dense masses of infantry, battery after battery of heavy artillery and troop upon troop of cavalry they rode toward the northeast.

They were not yet at the front of the long battle line, for General French had his headquarters well back, but still close enough to be in constant danger from the enemy’s artillery fire.

From a trot the troop broke into a gallop, and soon were beyond the farthest trenches.  Skirting this at the extreme north—­close to the sea—­they progressed still further toward the enemy.  It was the boys’ duty, if possible, to find out the position of the German forces at this point and to determine their numbers; also the strategic positions that could be used by either army.

Now an order was given for the troop to spread out, and, leaving the road, the two lads led their men into the woods, where they could advance with less danger of being seen.  They had not been ordered forward to give battle, and there would be no fighting unless it became necessary in order that their mission might be successful.

But, as in most missions upon which the lads had been dispatched, there was to be fighting; and these British were not the men to turn their backs upon the enemy without giving them a warm reception.

From the shelter of the sand dunes there came suddenly a fusillade.  Two British troopers reeled in their saddles and tumbled to the ground.

CHAPTER II.

A bit of history.

While Hal and Chester and their troop of British cavalry are preparing to meet this unexpected attack, it will be well to introduce here a few words relating to the positions of the gigantic armies battling in France and Belgium.

The war had now been in progress for five months.  From the time that the Allies had braced and checked the Germans in their rapid advance upon Paris, and had assumed the offensive themselves, they had progressed consistently, if slowly.