If one examines the map, it will be seen that by his inflection toward Meaux and Coulommiers General von Kluck was exposing his right to the offensive action of the French left. This is the starting point of the victory of the Marne.
On the evening of September 5th the French left army had reached the front Penchard-Saint-Souflet-Ver. On the 6th and 7th it continued its attacks vigorously with the Ourcq as objective. On the evening of the 7th it was some kilometers from the Ourcq, on the front Chambry-Marcilly-Lisieux-Acy-en-Multien. On the 8th, the Germans, who had in great haste reinforced their right by bringing their Second and Fourth army corps back to the north, obtained some successes by attacks of extreme violence. But in spite of this pressure the French held their ground. In a brilliant action they took three standards, and being reinforced prepared a new attack for the 10th. At the moment that this attack was about to begin the enemy was already in retreat toward the north. The attack became a pursuit, and on the 12th the French established themselves on the Aisne.
Why did the German forces which were confronting the French, and on the evening before attacking so furiously, retreat on the morning of the 10th? Because in bringing back on the 6th several army corps from the south to the north to face the French left, the enemy had exposed his left to the attacks of the now rested British, who had immediately faced around toward the north, and to those of the French armies which were prolonging the English lines to the right. This is what the French command had sought to bring about. This is what happened on September 8th and allowed the development and rehabilitation which it was to effect.
On the 6th the British army set out from the line Rozcy-Lagny and that evening reached the southward bank of the Grand Morin. On the 7th and 8th it continued its march, and on the 9th had debouched to the north of the Marne below Chauteau-Thierry—the town that was to become famous for the American stand in 1918—taking in flank the German forces which on that day were opposing, on the Ourcq, the French left army. Then it was that these forces began to retreat, while the British army, going in pursuit and capturing seven guns and many prisoners, reached the Aisne between Soissons and Longueval.
The role of the French army, which was operating to the right of the British army, was threefold. It had to support the British attacking on its left. It had on its right to support the center, which, from September 7th, had been subjected to a German attack of great violence. Finally, its mission was to throw back the three active army corps and the reserve corps which faced it.
On the 7th, it made a leap forward, and on the following days reached and crossed the Marne, seizing, after desperate fighting, guns, howitzers, mitrailleuses, and a million cartridges. On the 12th it established itself on the north edge of the Montagne-de-Reime in contact with the French center, which for its part had just forced the enemy to retreat in haste.
The French center consisted of a new army created on August 29th and of one of those which at the beginning of the campaign had been engaged in Belgian Luxemburg. The first had retreated, on August 29th to September 5th, from the Aisne to the north of the Marne and occupied the general front Sezanne-Mailly.
The second, more to the east, had drawn back to the south of the line
Humbauville-Chateau-Beauchamp-Bignicourt-Blesmes-Maurupt-le-Montoy.
The enemy, in view of his right being arrested and the defeat of his enveloping movement, made a desperate effort from the 7th to the 19th to pierce the French center to the west and to the east of Fere-Champenoise. On the 8th he succeeded in forcing back the right of the new French army, which retired as far as Gouragancon. On the 9th, at 6 o'clock in the morning, there was a further retreat to the south of that village, while on the left the other army corps also had to go back to the line Allemant-Connantre.
Despite this retreat General Foch, commanding the army of the center, ordered a general offensive for the same day. With the Morocco division, whose behavior was heroic, he met a furious assault of the Germans on his left toward the marshes of Saint Gond. Then, with the divisions which had just victoriously overcome the attacks of the enemy to the north of Sezanne, and with the whole of his left army corps, he made a flanking attack in the evening of the 9th upon the German forces, and notably the guard, which had thrown back his right army corps. The enemy, taken by surprise by this bold maneuver, did not resist, and beat a hasty retreat. This marked Foch as the most daring and brilliant strategist of the war.