Battle of the Frontiers in the context of "Battle of Mons"

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.

The Race to the Sea (French: Course à la mer; German: Wettlauf zum Meer, Dutch: Race naar de Zee) took place from 17 September to 19 October 1914 during the First World War, after the Battle of the Frontiers (7 August – 13 September) and the German advance into France. The invasion had been stopped at the First Battle of the Marne (5–12 September) and was followed by the First Battle of the Aisne (13–28 September), a Franco-British counter-offensive. The term describes reciprocal attempts by the Franco-British and German armies to envelop the northern flank of the opposing army through the provinces of Picardy, Artois and Flanders, rather than an attempt to advance northwards to the sea. The "race" ended on the North Sea coast of Belgium around 19 October, when the last open area from Diksmuide to the North Sea was occupied by Belgian troops who had retreated after the Siege of Antwerp (28 September – 10 October). The outflanking attempts had resulted in a number of encounter battles but neither side was able to gain a decisive victory.

After the opposing forces had reached the North Sea, both tried to conduct offensives leading to the mutually costly and indecisive Battle of the Yser from 16 October to 2 November and the First Battle of Ypres from 19 October to 22 November. After mid-November, local operations were carried out by both sides and preparations were made to take the offensive in the spring of 1915. Erich von Falkenhayn, Chief of the German General Staff (Oberste Heeresleitung OHL) since 14 September, concluded that a decisive victory could not be achieved on the Western Front and that it was equally unlikely in the east. Falkenhayn abandoned Vernichtungsstrategie (strategy of annihilation) and attempted to create the conditions for peace with one of Germany's enemies, by Ermattungsstrategie (strategy of exhaustion), to enable Germany to concentrate its resources decisively to defeat the remaining opponents.