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 August 10 under my personal command. While American units had held different divisional and corps 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 August 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 afterwards extended across the Meuse to the western edge of the Argonne Forest, and included the Second Colonial French, which held the point of the salient, and the Seventeenth French Corps, which occupied the heights above Verdun.
PREPARATION FOR THE ATTACK.
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 of 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, with its personnel, and we were confident from the start of our superiority over the enemy in guns of all calibers. 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 aviation that had ever been engaged in one operation on the western front.
LOCATION OF THE TROOPS.
From Les Eparges around the nose of the salient at St. Mihiel to the Moselle River the line was roughly forty miles long and situated on commanding ground greatly strengthened by artificial defenses. Our First Corps (Eighty-second, Ninetieth, Fifth, and Second Divisions), under command of Maj. Gen. Hunter Liggett, restrung its right on Pont-a-Mouson, with its left joining our Third Corps (the Eighty-ninth, Forty-second, and First Divisions), under Maj. Gen. Joseph T. Dickman, in line to Xivray, were to swing in toward Vigneulles on the pivot of the Moselle River for the initial assault. From Xivray to Mouilly the Second Colonial French Corps was in line in the center and our Fifth Corps, under command of Maj. Gen. George H. Cameron, with our Twenty-sixth Division and a French division at the western base of the salient, were to attack three difficult hills—Les Eparges, Combres, and Amaramthe. Our First Corps had in reserve the Seventy-eighth Division, our Fourth Corps the Third Division, and our First Army the Thirty-fifth and Ninety-first Divisions, with the Eightieth and Thirty-third available. It should be understood that our corps organizations are very elastic, and that we have at no time had permanent assignments of divisions to corps.
MOVEMENT OF THE TROOPS.
After four hours' artillery preparation, the seven American divisions in the front line advanced at 5 A.M. on September 12, assisted by a limited number of tanks manned partly by Americans and partly by the French. These divisions, accompanied by groups of wire cutters and others armed with bangalore torpedoes, went through the successive bands of barbed wire that protected the enemy's front line and support trenches, in irresistible waves on schedule time, breaking down all defense of an enemy demoralized by the great volume of our artillery fire and our sudden approach out of the fog.
Our First Corps advanced to Thiaucourt, while our Fourth Corps curved back to the southwest through Nonsard. The Second Colonial French Corps made the slight advance required of it on very difficult ground, and the Fifth Corps took its three ridges and repulsed a counter-attack. A rapid march brought reserve regiments of a division of the Fifth Corps into Vigneulles in the early morning, where it linked up with patrols of our Fourth Corps, closing the salient and forming a new line west of Thiaucourt to Vigneulles and beyond Fresnes-en-Woevre. At the cost of only 7,000 casualties, mostly light, we had taken 16,000 prisoners and 443 guns, a great quantity of material, released the inhabitants of many villages from enemy domination, and established our lines in a position to threaten Metz. This signal success of the American First Army in its first offensive was of prime importance. The Allies found they had a formidable army to aid them, and the enemy learned finally that he had one to reckon with.