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 the 5th to the 12th 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 (Allies/Entente). 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 Franco/British forces more than 250 km (160 mi) southward. 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 his French allies and began to plan for a British retreat to port cities on the English Channel for an evacuation to Britain. However, the French commander Joseph Joffre maintained good order in his retreating army and was able to reinforce it by bringing in additional manpower from his eastern flank and 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 Simon Gallieni, perceived that the German right flank was vulnerable and positioned his forces to attack.
On 4 September Joffre gave the order to launch a counteroffensive. The battle took place between Paris and Verdun, a west to east distance of 230 km (140 mi). The point of decision and the heaviest fighting was in the western one-half of that area. By 9 September, the success of the Franco–British counteroffensive left the German 1st and 2nd Armies at risk of encirclement, and they were ordered to retreat to the Aisne River. The retreating armies were pursued by the French and British. The German armies ceased their retreat after 65 km (40 mi) on a line north of the Aisne River, where they dug in on the heights and fought the First Battle of the Aisne. The German retreat from 9 to 12 September marked the end of the German attempt to defeat France quickly. Both sides next commenced reciprocal operations to envelop the northern flank of their opponent in what became known as the Race to the Sea which culminated in the First Battle of Ypres and led to a bloody four-year long stalemate of trench warfare on the Western Front of World War I.
