(Sept. 26–Nov. 11, 1918), a series of final confrontations on the Western Front in World War I.

Following the German retreat from the Marne River in July, General Ferdinand Foch and the Allied high command designed a series of convergent and practically simultaneous offensives against the shaken German armies. One was a joint operation in the Meuse valley toward the Mézière and Sedan rail centre. The Americans proceeded west of the Meuse River, the French west of the Argonne Forest. The Americans faced the most difficult natural obstacle, the dense Argonne Forest. General John Pershing's opening surprise attack advanced 5 miles (8 km) along the Meuse River but only 2 miles (3 km) in the difficult Argonne Forest sector. Attack after attack edged deeper into the Germans' defensive position, and on the 11th day of the American offensive, the Germans recognized that they were outflanked and retreated to avoid capture. Meanwhile the French advanced steadily across the Aisne lowlands. By October 31 the American forces had advanced 10 miles (16 km), the French had advanced 20 miles (32 km), and the Argonne had been cleared of German troops.

Hard fighting continued in the Meuse-Argonne sector during October. More than a million Americans participated in the battles, but the American Expeditionary Force's casualties were heavy, and its largely inexperienced formations were becoming increasingly disorganized. On November 10 the Allies reached Sedan and cut the rail line there. The Armistice was declared (November 11) before a final offensive against Germany itself could begin.