Nothing remained but to endeavor to engulf the French armies. The Germans deemed this impossible in the east, because of the supposed heavy concentration of French troops there, because of the strength of Verdun and because of the defeat at Nancy. The flanking movement, therefore, must be made in the west. This could only be done by driving a wedge down between Paris and the Fifth French Army, heavily reënforced and now under the command of General d'Esperey. This gap was held by the British, against whom the Germans had a special hate.
Von Kluck and Von Buelow had not reached their advanced positions easily. They had been severely mauled in two defeats, at Le Cateau and at Guise. In a war of less magnitude, these would have appeared as great Allied victories, but Joffre preferred to lose the advantage of following up these victories for the greater advantage of falling back strategically in good order. Moreover, the forts of Maubeuge still held. It was not until the grim old warrior Von Zwehl, with superhuman energy, brought up the great siege-guns, that Maubeuge fell. It was then too late for the guns to be of any service in the Battle of the Marne.
That Saturday afternoon, learning from air scouts that Von Kluck had massed his forces to the south, in order to attack the British on the morrow and pierce the gap, Manoury determined to force the issue. He launched his small and war-wearied army against the reserve which Von Kluck had left behind to guard the crossing of the Ourcq. The western end of the Battles of the Marne had begun.
Two important results developed immediately. One was Manoury's discomfiting discovery that the German heavy artillery gave the invaders a tremendous advantage when great mobility was not needed, as, for example, in defense of the crossings of a stream. The other was Von Kluck's discomfiting discovery that Manoury's army, attacking his reserves, was far stronger in fighting power than he thought. Each of these surprises counterbalanced the other.
This same Saturday afternoon, moreover, at the time that Manoury attacked, Von Kluck, from the other wing of his army, had sent a scouting party of cavalry to find out the location of the British Army. It was an excellent opportunity to cut them up, but the British Field Marshal had drawn his troops into cover of the forests and he let the scouts go by. A courier, detached from time to time, took to Von Kluck the welcome news that the British were nowhere to be seen and that the hoped-for gap existed. The British chuckled with glee. Von Kluck, surer every moment of flanking the Fifth French Army, hurried his men southward.
Suddenly, however, that Saturday evening, Von Kluck received word of the Manoury attack and realized that his reserves were threatened and his own flank was in danger. His men had marched all day. A large section of his army had to march back all night to reënforce the reserves attacked by Manoury.
Horace, through his experience on the battle front, had learned that a motor-cyclist's greatest usefulness is at dawn or a little before. This is due to that fact that, when an army is on the move, telegraph cable is laid from division to brigade headquarters and from brigade to battalion headquarters, as soon as these positions are determined for the night. This is done from cable wagons and the Signal Corps men are so deft that the cable can be laid as fast as horses can canter. At about three o'clock in the morning, if headquarters are going to move, this cable is picked up, ready for use the coming night. Enemy assaults, however, are likely to begin at dawn and these may cause a change in the dispositions already decided on. It is then that the motor-cyclist dispatch-rider is especially valuable.
At three o'clock this morning of Sunday, September 6, Horace got up, put on the dead man's uniform, trundled out his motor-cycle and whizzed to General Gallieni's headquarters.