The First Battle of the Marne took place on a 300-mile front along the River Marne in the vicinity of Paris. The First Battle of the Marne was the first major Allied victory on the Western Front in the First World War. The battle took place from September 5 to September 12, 1914. During the preceding weeks, the allied forces had retreated until the Germans were only 10 miles from Paris. However, their supply lines were greatly stretched. During the battle, a dangerous gap opened between their first and second armies, which the British Expeditionary Force exploited on September 8. In order to avoid an encirclement, the Germans were forced to retreat. The German armies retreated to the Aisne. After the Battle of the Marne, both sides entrenched themselves and the war became a stalemate. For the rest of the war, the Germans never again had as good an opportunity to capture Paris.