We had also to consider the dispersion and the fatigue which bring loss of momentum in an attack, just as a tidal wave spends itself in flowing inland. The farther our infantrymen went, the farther our transport must go to provide them with rations and ammunition. Thus the ability of our organization to continue the advance after the "break through" included the indispensable factor of efficient arrangements at the rear. As a division has twenty-seven thousand men, its daily food requirements are equal to those of a good-sized town, without including small arms and artillery ammunition and other material. People at home who were surprised at the length of time it took a division to march by on parade, without its artillery or transport, will have some idea of the road space required for a single division fully equipped for action and in motion. Behind the old trench system traffic movement had settled into a routine, under the direction of policemen at the crossings, resembling that of a city. In our mobilization for the attack we had brought, aside from corps and army troops, nine divisions into the Meuse-Argonne sector. This led to the pressure which would appear in suddenly trebling the traffic of a city. Though the roads were insufficient, they were kept systematically in repair; quantities were known; we were forming up on a definite line of front. After the attack was begun, the defensive force was falling back upon its established and dependable arrangements. The offensive force--and this cannot be too clearly or vividly stated--had to build a city, as it were, by establishing new depots and camps, repairing old roads and building new roads, while traffic control in the area of advance was subject not only to the calculable requirements of a great street parade in a city, but to the incalculable requirements of a great fire and other emergencies which switch concentrations from one street to another. From a ridge in the midst of the old trench system in the center of our line, the nature of our task appeared as a picture, which my observation in threading my way through the streams of traffic in the rear filled in with detail. Ahead, except for occasional groups and lines appearing and disappearing in the wooded, undulating landscape, our advancing infantry seemed to have been dissipated into the earth. Their part after they were through the fortifications I shall describe in another chapter. The bridge between them and the rear was for the moment in the air, where Allied and German planes in prodigal numbers came and went on their errands of combat and observation. In the jam on the roads back of the trenches, thousands of men, of waiting machine-gun battalions and of stalled artillery, and drivers and helpers attached to traffic of all kinds, were looking aloft at a "show" which was worth the price of being packed in darkened transports, and almost worth the price of enduring army discipline.