The Second Battle of the Marne, or Battle of Reims (15th July – 6th August, 1918) was the last major German Spring Offensive on the Western Front during the First World War, in the final year of this conflict. On the morning of July 15th, then, 23 divisions of the German 1st and 3rd Armies attacked the French 4th Army east of Reims, while 17 divisions of the 7th Army, assisted by the 9th Army, attacked the French 6th Army to the west of the city. The dual attack was Ludendorff's attempt to divide and conquer the French forces, which were joined by 85,000 U.S. troops as well as a portion of the (BEF) British Expeditionary Force. The Germans began their advance after an initial artillery bombardment, however, they found that the French had set up a line of false trenches. The real front line of trenches lay further on, and had scarcely been touched by the bombardment. Casualties were high, more so among the German forces that the Allies. France suffered 95,000 casualties, with Britain incurring 13,000 losses and the U.S. 12,000. The Allies had taken 29,367 prisoners, 793 guns and 3,000 machine guns and inflicted 168,000 casualties on the Germans. The primary importance of the battle was its morale aspect: the decision gained on the Marne marked the end of a string of German victories. As a German officer, Rudolf Binding, wrote in his diary of the July 15th attack, the French "put up no resistance in front...they had neither infantry nor artillery in this forward battle-zone...Our guns bombarded empty trenches; our gas-shells gassed empty artillery positions....The barrage, which was to have preceded and protected [the attacking German troops] went right on somewhere over the enemy's rear positions, while in front the first real line of resistance was not yet carried." As the Germans approached the "real" Allied front lines, they were met with a fierce barrage of French and American fire. Second Battle of the Marne was seen as an Allied victory. After it became clear that the Germans had not only failed in their aim to win the war in this offensive, but had in fact lost ground, a number of German commanders, believed the war was lost. Thus the Second Battle of the Marne can be considered as the beginning of the end of the Great War.
Source Wiki, History.com