Fought between 12-15 September 1918, the reduction of the St. Mihiel salient was the first major offensive undertaken by the American Expeditionary Force. The salient had been taken by the Germans in their attempt to capture Verdun in 1916, and a number of attacks by the French had failed to retake it; its existence cut Verdun off from Nancy and made resupply of Verdun's defenders difficult.
General Pershing took personal command of the assault and brought maximum force to bear. In addition to the fourteen oversized divisions of the AEF, the French II Colonial Corps and 5th Colonial Division (under the American V Corps) would be in the attack. 144 tanks in two battalions under Colonel George S. Patton would be joined by the 275 tanks of the French 1st Assault Artillery Brigade, and almost 1500 allied aircraft.
Defending the salient was the German Army Detachment C, consisting of ten understrength divisions. The Germans were in the process of evacuating the salient for more defensible terrain, and the offensive hit them while they were in movement. By the morning of the 13th, the 1st and 26th Divisions had linked up, and by the evening of the 13th all objectives within the salient were in Allied hands. At this point, Pershing halted the operation so that troops could be withdrawn to prepare for the Meuse-Argonne offensive.
Credit for the smashing success of this operation belongs to Pershing, who had written an extremely detailed operations order specifying individual objectives for each corps and the use of combined arms tactics, and to his front-line commanders such as Patton, who led from the front and by example in contrast to the European habit of commanding from the rear.