On September 12, 1918, the American Expeditionary Forces under commander in chief General John J. Pershing launched their first major offensive in Europe as an independent army. General Pershing had placed the first American troops to land in Europe completely at the disposal of Marshall Ferdinand Foch, commander in chief of the French forces. Foch required immediate reinforcement of his troops in the Aisne-Marne region to halt the German Army's move towards Paris.
The American troops fought in the trenches alongside the fatigued French forces at the Battle of Belleau Wood and the Second Battle of the Marne. Once the allied French and American forces had succeeded in halting the German advance in the Aisne-Marne area, Foch and Pershing agreed that the First U.S. Army would establish a headquarters in the Saint-Mihiel sector. The German Army had occupied the area in fall 1914, and fortified the triangular wedge between Verdun and Nancy known as the Saint-Mihiel salient, effectively preventing rail transport between Paris and the Eastern Front.