210 The Great War cross to France without resistance, the German ex- pectation was to force the Verdun-Toul barrier, withdraw all German troops from Belgium and em- ploy the French lines, shorter and more satisfactory for German purposes, to transport supplies and re- enforcements to the forces operating south of the Marne and before Paris. Belgian resistance did not change the plan; in fact, it rather increased the urgency of the need for carrying the Verdun-Toul barrier. For until it was carried all Northern, Eastern and Central Belgium had to be garrisoned in order to keep open the rail- ways from Liege to Northwestern France, on which the armies of von Boehm, von Kluck and von Bue- low depended for all their supplies and reenforce- ments. Despite desperate efforts the first attack upon Ver- dun failed and the Crown Prince's army was in- volved in the general retirement after the Battle of the Marne. At the same time the attempt of von Heerlngen, despite the presence of the Kaiser, was halted in sight of Nancy. For the moment the plan had to be abandoned. But, just as soon as the Ger- mans had rallied on the Aisne line and reorganized, the operation was resumed, since for obvious reasons the need of forcing the barriers and releasing army corps In Belgium to meet the reenforced Allied troops along the Aisne was daily increasing. This time a less ambitious scheme was adopted. While the Crown Prince again came south between