AISNE-MARNE OPERATION, a French and American counteroffensive against the German army during World War I. In the spring of 1918, Germany launched a desperate effort to knock France out of the war before American forces arrived to support the French. The effort failed. By midsummer the German attack ground to a halt, and the arrival of thousands of fresh American troops made possible a major counterassault. The French Tenth Army opened the attack in mid-July, striking eastward into the salient just south of Soissons, France. The main attack was made by the Twentieth Corps, with three divisions on the front line, two American and one Moroccan. The attack took the Germans by surprise, and their outpost line made little resistance, but the line soon stiffened and the fighting was severe. It was not until 21 July that control of the Soissons-Château-Thierry highway was gained. The total penetration was eight miles.
From 21 July on, the armies farther east joined in the advance—the Sixth and the Fifth, along both faces of the salient. With the Sixth Army there were two U.S. corps headquarters—the First and the Third—and eight American divisions. The Germans conducted their retreat skillfully, making an especially strong stand on the Ourcq River on 28 July. But early in August they were back behind the Vesle River, which they would not cross again.
The Aisne-Marne Operation changed the complexion of the war. A German offensive had been stopped suddenly in mid-onslaught, and the advance changed to a retreat. The Marne salient had ceased to exist, and the Germans were never again able to undertake a serious offensive. The addition of hundreds of thousands of American troops to the Allied cause made further German resistance futile. In November, facing economic collapse at home and the combined forces of Britain, France, and the United States on the battlefield, Germany finally surrendered.
Keegan, John. The First World War. New York: Knopf, 1999.
Oliver LymanSpaulding/a. g.