The Allies’ left, confronting this position, held strong reserves, and by the nature of the ground itself, was well placed to prevent any enveloping movement, dear to the German school of military tactics.  It rested securely on the fortress of Paris, believed by its constructors to be the most fully fortified city in the world, and should the German right endeavor to encircle the left wing of the Allies, should it develop a farther westerly movement, it would but come in contact with the outer line of those defenses and thence be deflected in such an enormous arc as to thin the line beyond the power of keeping it strong enough to resist a piercing attack at all points.  Clearly, then, as long as the extreme left of the Allies remained in contact with the defenses of Paris, an enveloping movement was not possible on the easterly flank.

Facing the German extreme right, was the Sixth French Army, one of the great reserves of General Joffre, which had been steadily building up since August 29, 1914, with its right on the Marne and its left at Betz, in the Ourcq Valley, encamped on the western side of that stream, facing the Second and Fourth Corps of the Germans.  The strengthening of that army from the forces at Paris was hourly, and while three or four days before it had been felt that the Sixth French Army was too weak to be placed in so vital a point—­that it should have been supplemented with the Ninth Army—­the results justified the French generalissimo’s plans and more than justified his confidence in the British Army, or Expeditionary Force, which faced the tip of the German right wing drive and was encamped on a line from Villeneuve le Comte to Jouy le Chatel, the center of the British army being at a point five miles southeast of Coulommiers.  This army was under the command of General Sir John French.

The right center of the German line was held by General von Buelow’s army, consisting of the Ninth Corps, the Tenth Corps, the Tenth Reserve Corps, and the Guard Corps.  This army also was encamped upon the Marne, stretching from the eastern end of General Von Kluck’s army as far as Epernay.  This army thus held the Forests of Vassy but was confronted by the marshes of St. Gand.

Confronting this right center was, first of all, General Conneau’s Cavalry Corps, which was in touch with the right wing of the British army under Sir John French.  Then, holding the line from Esternay to Courtacon lay the Fifth French Army under General d’Esperey.  Full in face of the strongest part of the German right center stood one of the strongest or General Joffre’s new reserves, the Ninth Army under General Foch, with the marshes of St. Gond in front or him, and holding a twenty-mile line from Esternay, past Sezanne to Camp de Mailly, a remarkably well-equipped army, very eager for the fray.