Joseph Simon Gallieni in the context of Michel Maunoury

The First Battle of the Marne or known in France as the Miracle on the Marne (French: miracle de la Marne) was a battle of the First World War fought from 5 to 12 September 1914. The German army invaded France with a plan for winning the war in 40 days by occupying Paris and destroying the French and British armies. The Germans had initial successes in August. They were victorious in the Battles of Mons and the Frontiers and overran a large area of northern France and Belgium. In what is called the Great Retreat the Germans pursued the retreating French and British forces more than 250 km (160 mi) southwards. The French and British halted their retreat in the Marne River valley, while the Germans advanced to 40 km (25 miles) from Paris.

With the battlefield reverses of August, Field Marshal John French, commander of the British Expeditionary Force (BEF), lost faith in the French and began to plan for a British retreat to port cities on the English Channel for an evacuation to Britain. Joseph Joffre, the French commander, maintained good order in his retreating army and was able to reinforce it with troops from his eastern flank and by integrating military reserve units into the regular army. By early September, the Franco–British forces outnumbered the Germans, who were exhausted after a month-long campaign, had outrun their supply lines and were suffering shortages. On 3 September, the military governor of Paris, Joseph Gallieni, perceived that the German right flank was vulnerable and positioned his forces to attack.