The first Battle of the Marne took place between 5th and 11th September, 1914. The most important consequence of the battle was that the French and British forces were able to prevent the German plan for a swift and decisive victory.
The second major battle close to the River Marne took place during the summer of 1918. During the Spring Offensive, the German Army advanced over the Aisne in late May and reached the Marne on 5th June. The French Army was in poor shape and the Commander-in-Chief, Henri-Philippe Petain, knew that the British were busy dealing with the German offensive at Lys. Eventually Sir Douglas Haig agreed to send Petain four divisions and two divisions of the recently arrived US Army were also available. Over 85,000 American soldiers took part in the battle.
The German attack on the Marne was launched by General Erich von Ludendorff on 15th July. Twenty-three divisions of the First and Third Armies attacked the French Fourth Army in the east of Reims and seventeen divisions of the Seventh army took on the French Fifth Army to the west.
The Germans failed to break through and General Ferdinand Foch was able to organize a counterattack. This included 24 divisions of the French Army, and soldiers from the United States, Britain and Italy. On 20th July the Germans began to withdraw. By the 3rd August they were back to where they were when they started the Spring Offensive in March.
Allied casualties during the 2nd Battle of the Marne were heavy: French (95,000), British (13,000) and United States (12,000). It is estimated that the German Army suffered an estimated 168,000 casualties and and marked the last real attempt by the Central Powers to win the First World War.