Following even more training in northeastern Dijon, on August 24, the 90th Infantry Division entered a sector of the front on the eastern side of the St. Mihiel salient. At the time Pershing, now a full general and Commander-in-Chief (C-in-C) of the AEF on the Western Front, was getting ready for his first major offensive–closing off the salient. Allen's unit was to form the right pivot in the offensive. It started early on September 12 when the offensive began. After a rolling barrage, the division kept moving ahead. Over the next nine hours, Allen's men captured their objectives and by September 16, the Americans had reduced the salient. After the salient was eliminated, Pershing planned for the American forces to attack west at Meuse-Argonne. In the beginning, Allen's unit stayed close to St. Mihiel, covered sectors already left vacate by the troops who went west, and grouped together their positions. Once the battle had become more intense, Allen and his men entered the lines close to Bantheville. The 90th advanced slowly and Allen relieved officers who he found to be incompetent or weak. The division was able to get through the Meuse River near Stenay only several days before the signing of the Armistice of November 11, 1918.