The Battle of the Marne by G.H. Perris — Read

The first fact which had to be reckoned with was that the main weight of the enemy was bearing down across the north and north-east, and was, for the moment, irresistible. Retreat, at the outset, was not, then, within the plan, but a condition of it. There was no choice; contact with the invader must be broken if any liberty of action was to be won back. Defeat and confusion had been suffered at so many points, the force of the German offensive was so markedly superior, that an unprepared arrest on the Belgian frontier would have risked the armies being divided, enveloped, and destroyed piecemeal.

If the first stage of the retreat was enforced, its extension was in some measure willed and constantly controlled. For all the decisions taken, Joffre must have the chief credit, as he had the whole responsibility. The abandonment of large tracts of national territory to a ruthless enemy cannot be an easy choice, especially when the inhabitants are unwarned, and the mind of the nation is wholly unprepared (the defeats on the Sambre and the Meuse were not known for several days to the civil public, and then only very vaguely). A less cool mind might have fallen into temporising expedients. Maubeuge was to hold out for a fortnight more; the 4th Army had checked the enemy, and Ruffey had repulsed several attacks; Longwy had not yet capitulated. But the Commander-in-Chief was not deceived. He had no sooner learned the weight of Kluck's flying wing than he realised that the only hope now lay in a rapid retirement.