The Second Battle of the Marne was the turning point of the First World War on the Western Front. It began as a German offensive (the Champagne-Marne Offensive, 15-18 July) but ended with a successful Allied counter-attack (the Aisne-Marne Offensive, 18 July-5 August) which saw the German army pushed back almost to the line it had occupied before their great success during the Third Battle of the Aisne, the third of Ludendorff’s great offensives of 1918.
Ludendorff’s Aisne offensive of May 1918 had driven the French back across the Aisne and had briefly threatened to cross the Marne, before finally running out of steam as French and American opposition stiffened. He had hoped that the attack on the Aisne would draw Allied reserves south and allow him to break through the British lines in Flanders. His aim was to split the British and French armies apart and reach the channel ports. Instead, in the aftermath of the victory on the Aisne Ludendorff had launched a fourth offensive (Noyon-Montdidier, June 1918), designed to link the Marne salient with the equally large salient created on the Somme in the first of the offensives (Second Battle of the Somme, March 1918). This offensive had ground to a halt after less than a week, leaving Ludendorff to decide where to make his next attack.
His two options were an attack in Flanders, which held out the prospect of gaining a real advantage in the war, or an easier attack towards Paris from the Marne salient. He chose the second option. The attack would be launched by 52 Divisions from three armies. The 7th Army under General Max von Boehn would attack west of Rheims, while the 1st (General Bruno von Mudra) and 3rd (General Karl von Einem) would attack east of the heavily fortified city. The two prongs of the German attack would unite to the south of Rheims. Ludendorff would then be able to move more troops north for sixth offensive in Flanders.
The attacks east of Rheims were quickly halted. West of Rheims the Germans advanced across the Meuse and formed a shallow salient nine miles long and four deep. This part of the battle, south of the Marne and south west of Rheims is sometimes known as the Second Battle of the Marne itself. The French 5th Army was then reinforced by the French 9th Army and the American 2nd Division and the German advance was held.
General Foch had already been planning a big counterattack before the German attack across the Marne. On 18 July units from three French armies, along with the American 1st and 2nd Divisions, under the overall command of General Mangin, launched a counterattack along the entire Marne salient. The Germans were quickly forced out of their footholds south of the Marne and began to retreat across ground captured in the Aisne offensive. Soissons, in the north west corner of the salient, was liberated on 2 August. Ludendorff was now faced with the real prospect of his armies in the salient being cut off, and was forced to order a retreat north east out of the salient to a new line along the rivers Aisne and Vesle. On 6 August the Americans attacked the new German line and were repulsed. Fighting then died down along the new front line.
Ludendorff’s five offensives had come close to breaking the Allied line, but they had always been a gamble. Ludendorff was aware that millions of American soldiers were gathering in France. If Germany was to win the war, it would have to be before all of those fresh troops could enter the line. The Germans suffered some 800,000 casualties during Ludendorff’s offensives. Allied losses were similar, but the Allies could now replace their losses while the Germans could not. On 8 August the Allies would launch their own great offensive at Amiens, described by Ludendorff as the Black Day of the German Army. The static Western Front was finally moving.