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

General Joffre's Instruction of September 1 had prescribed that the whole offensive should pivot upon the right. The defence of the eastern front, as a wall protecting the western and central armies, and the pivot of their recoil -- essential condition of the general success -- was assigned to Generals de Castelnau and Dubail. The 2nd and 1st Armies had been severely punished at the outset of the campaign; and, evidently, a heavy task now lay before them. The second of the German princes, Ruprecht of Bavaria, with the last corps of the Bavarian Army, could not be given other than a principal rôle; and Heeringen, chief of the 7th Army, Prussian War Minister during a critical part of the period of preparation, was also a veteran of the Grand Staff, with which he had worked for more than thirty years. On September 6, the Grand Quartier General specified that Castlenau and Dubail should remain on their positions defensively till the end of the battle of the Marne.

We have seen that, after the failure of the offensives of Morhange–Sarrebourg and Mulhouse, the two armies retreated rapidly, but in such a way that, taking up an angular formation from the Grand Couronné of Nancy southward to the Gap of Charmes, and thence eastward to the Donon, they were able, on August 25, to fall upon the two flanks of the advancing enemy with instant effect. There was then a pause, due in part to heavy fogs, for several days, in which either side prepared for a new encounter.