With the reduction of the Marne salient, we could look forward to the concentration of our divisions in our own zone. In view of the forthcoming operation against the St. Mihiel salient, which had long been planned as our first offensive action on a large scale, the First Army was organized on Aug. 10 under my personal command. While American units had held different sectors along the western front, there had not been up to this time, for obvious reasons, a distinct American sector; but, in view of the important parts the American forces were now to play, it was necessary to take over a permanent portion of the line. Accordingly, on Aug. 30, the line beginning at Port sur Seille, east of the Moselle and extending to the west through St. Mihiel, thence north to a point opposite Verdun, was placed under my command. The American sector was afterward extended across the Meuse to the western edge of the Argonne Forest, and included the 2d Colonial French, which held the point of the salient, and the 17th French Corps, which occupied the heights above Verdun. The preparation for a complicated operation against the formidable defenses in front of us included the assembling of divisions and of corps and army artillery, transport, aircraft, tanks, ambulances, the location of hospitals, and the molding together of all the elements of a great modern army with its own railheads, supplied directly by our own Service of Supply. The concentration for this operation, which was to be a surprise, involved the movement, mostly at night, of approximately 600,000 troops, and required for its success the most careful attention to every detail. The French were generous in giving us assistance in corps and army artillery and we were confident from the start of our superiority over the enemy in guns of all calibres. Our heavy guns were able to reach Metz and to interfere seriously with German rail movements. The French Independent Air Force was placed under my command, which, together with the British bombing squadrons and our air forces, gave us the largest assembly of aviators that had ever been engaged in one operation on the western front.