At daybreak on Sunday, the 6th, Foch pitched his headquarters in a modern château near the little village of Pleurs, which you probably will not find on any map except a military one, but it is some six miles southeast of Sézanne. And the front assigned to Foch ran from Sézanne to the Camp de Mailly, twenty-five miles east by a little south. The Marne was twenty-five miles to north of him. Between him and its south bank were many towns and villages; the clay pocket (ten miles long) called the Marshes of St. Gond, but far from marshy in that parching heat; and north of that the forest of Epernay. His vanguards were north of the marshes. But as that Sunday wore on, the Prussian Guards drove Foch's Angevins and Vendeans of the Ninth Corps back and occupied the marshes. The Bretons on the east of Foch's line were obliged to dislodge, and the Moroccans and Forty-second Division had to yield on Foch's left.
Thus, at nightfall of the first day's fighting, Foch's new army had given ground practically everywhere.
The next day the German attack became fiercer, and it seemed that more ground must be yielded.
That was the day when Foch made his memorable deduction: "They are trying to throw us back with such fury I am sure that means things are going badly for them elsewhere and they are seeking compensation."
He was right! Von Kluck was retiring in a northeasterly direction under Manoury's blows; and even Von Buelow (whom Foch faced) was withdrawing parts of his troops from the line at Foch's left.
But the attempt to break through the center Foch held, waxed fiercer as the Germans realized the strength opposing them on their right.
And on Tuesday, the 8th, Foch was unable to hold—save at certain points—and had to move his headquarters eleven miles south, to Plancy.
He had now reached the Aube, beyond which Joffre had decreed that he must not retire. On its north bank his gallant army must, if it could not do otherwise, "allow itself to be slain where it stands rather than give way."
On that evening he sent Major Réquin to the Forty-second Division with orders for the morrow. The most incredible orders!
The enemy had found his point of least resistance—on his right wing. He ought to strengthen that wing, but he could not. All the reserves were engaged—and the enemy knew it as well as he did. And it is a fixed principle of war not to withdraw active troops from one part of the line to strengthen another.