The other factor depended on the vexed question of means of communication. There was no cross-country railway linking the eastern German wing to the western German wing. As has been previously remarked, all supplies and munitions had to come in a roundabout way. Verdun was a desired goal, but Field Marshal von Heeringen was wise enough to know that if the crown prince's effort against General Sarrail had failed, if the Third French Army had secured heavy reenforcement, and if it had been left unmolested for a week, the outer ring of defenses around Verdun would, by that time, have become so amazingly strengthened that direct or frontal attack would be impossible, while the flanking attack had failed. It was vain, therefore, at the present time, to hope that the establishment of the direct communication between Metz and Verdun might pass into the hands of the invaders. On the other hand, there was a direct line of railway running through Rheims, Rethel, Mezieres to the great war depot, Coblenz on the Rhine. A branch line from Metz, through Luxemburg, thus gave communication to the eastern wing. All the links of this were in German hands, except Rheims, and if that railroad center could be secured, the importance to the German advance would be enormous. Under such circumstances, it can scarcely be held that Rheims was not necessarily a point, the attack of which was due to military necessity. The formation for this began on September 17, 1914. Crossing the Aisne by the old ford of Berry-au-Bac, a powerful army under the direct leadership of Field Marshal von Heeringen debouched upon the open country between Berry-au-Bac and Suippes, east of Rheims. It was at this point that the German commander in chief of this section of the battle line intended to deliver a crushing blow by which might be regained the prestige secured at Charleroi and lost again at the Marne. Surprise may be felt that so important a railway center as Rheims should not have been a strongly fortified place. It had been so once, though the fortifications were old-fashioned. But, instead of bringing these points of natural defense up to the highest degree of modern efficiency, the French had dismantled them entirely, so as to make Rheims with its glorious cathedral an open town, safe from bombardment. It was, according to the rules of war, safe from bombardment, but only in the event of its not being defended. General Foch did not dare to take this stand. He knew, as well as did General von Heeringen, the strategic value of Rheims as railroad center, and accepted the issue of battle.