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. The circumstances differed considerably from those in the west. For their abortive offensives, the two armies had been given a distinct superiority of force on the eastern frontier; but, after the successful defence of the Gap of Charmes, this superiority had been drawn upon repeatedly by the Generalissimo to feed his main design. Thus, Castlenau had sent from the 2nd Army: on August 15, the 18th Corps, to Lanrezac, for the advance to the Sambre; on August 18 and September 4, the 9th Corps, to the 4th Army, from which it was detached to Foch’s Army of the centre; on September 3, the 15th Corps, to Sarrail; and on September 1, the greater part of the 2nd Cavalry Corps, to the space between the British and French 5th Armies. At the same time, Dubail, while absorbing gradually the body of Pau’s “Army of Alsace,” sent the 21st Corps, on September 4, to Langle’s left, and the 13th Corps, on September 9, to the region of Compiègne for the battle of the Aisne; after which, in the middle of September, when the great victory had been won, the 1st Army took over the whole of the Nancy front from the 2nd Army. These deplacements were necessary, and remarkably timed and executed; but they represent a not inconsiderable diminution of effective strength at a grave juncture. To compensate for their losses, the High Command could only send to the Lorraine Armies divisions of reserves. Their performance surpassed all French, and rather justified German, anticipations. It is, however, to be remarked that