The S. O. S. had been arranged to meet the demands of an army in our own sector. Its plan was disrupted by the switching of our troops to Château-Thierry and Picardy to meet the German offensives. The mobilization for Saint-Mihiel brought us back to our own sector. After Saint-Mihiel came the Argonne concentration, called into being by the hope of a speedy end of the war through one supreme effort by all the Allies. Should our new troops, thrown in action without sufficient preparation, and the veteran troops, thrown in without time for recuperation after Château-Thierry and Saint-Mihiel, go without food and ammunition, we might have a disaster. The wisdom of our insistence that we could form and supply and fight an integral army, instead of infiltrating our men into the British and French armies, was on trial. Victory and our soldiers' lives were at stake. The battle was to be fought not only against machine-gun nests, but in the sweating effort of stevedores, of mechanics, and laborers, in the roar of foundries, in the rattle of trains far from the sound of the guns. For officer personnel in the S. O. S. we had first, of course, the regulars, those of the old quartermaster department and of the engineers, who would not ordinarily command troops, and those who could be spared from the zone of advance where every able fighting officer was required. These must be few, compared to the numbers of the whole. Second, we had all the men in the thirties, forties, and fifties, experts in every calling, who had come to France in their enthusiasm, in answer to the summons, in the days when the thing was for every man to serve in uniform in France. These were too old for combat, even if they thought they were not. They could not stand the physical hardship of the front, however brave their spirit. The S. O. S. was the place for them. There, or in building the organization of supply at home--which was primarily important--the nation could make the best use of their training in civil life. Third were younger officers, from the Guard or a training-camp, caught by the card-index system classifying occupations, and separated from their regiments because they were experts in some line of activity which was short of personnel in the S. O. S. They knew how to fight; but their knowledge of something else, their superiors thought, not they, was more useful to the nation. For mechanics we had all the men skilled in trades at home who were as ready to give up high wages for a soldier's pay, and to work double union hours, as they would have been to stick tight in a fox-hole against a counter-attack, if they had had the chance. These came in their thousands, living under conditions far more miserable, in contrast to their habits, than their officers--from railroad trains and shops, bakeries, cement factories, contractors' firms, and every industry on the list--the typical American army, which has made industrial America.