The Seed of Empire by Fred M. White

This was the problem that faced the supreme commander of the British Expeditionary Force and his lieutenants, Smith-Dorrien and Haig. What they resolved upon we may know when the history of the great fight comes to be written by those in a position to know. So far as we can tell there was no fighting the next day, though the British were in hourly expectation of it, but eyewitnesses say that during the morning there was a strange slackness and want of cohesion in the German attack, and suddenly the news spread that von Kluck had turned his front facing east and was in full retreat from Paris. This was the welcome information that one after another of the aviators brought to Headquarters. Then gradually it leaked out that Joffre had masked a whole army to the east of Paris, with which, incredible as it may seem, von Kluck and his army were almost in touch before they were even aware of its existence. It was almost beyond credence that the German spy system should have broken down so badly just when its information would have been of the utmost value. And thus almost in the twinkling of an eye, the peril which had menaced the existence of the British army resolved itself into the promise of annihilation for the forces of von Kluck. Had he remained in ignorance of his danger for a few hours longer a good deal of recent history would have been very different.

But there was no getting away from the fact that the enemy was in full retreat all along the line, and that for the moment at any rate the menace to France and Paris was lifted. Here was French's chance, and he took it without the slightest hesitation. He had promised his men a fight under conditions fairly favourable to them, and now he struck with all his might. It looked as if the retreat from Mons was about to be followed by a big advance along the same lines. At the same moment the French army at Paris was moving up against von Kluck's rearguard--moved up not in the ordinary way by forced marches, but much as the average man finds his way to a railway station. It was an army moving in taxi-cabs and motor-cars, and moving so swiftly that within five days the Germans were pushed back from the gates of Paris across the strong lines of the Marne, right up to the Aisne, and from that day the reconquered plains of France have seen nothing of them.