The First Battle of the 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 (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 mi) from Paris.
9 September 1914. The BEF (brown) and French 5th army (red) exploit the gap between the German 1st and 2nd armies.
French infantry charge, 1914
The British Expeditionary Force (BEF) was the six divisions the British Army sent to the Western Front during the First World War. Planning for a British Expeditionary Force began with the 1906–1912 Haldane Reforms of the British Army carried out by the Secretary of State for War Richard Haldane following the Second Boer War (1899–1902).
British troops from the 4th Battalion, Royal Fusiliers (City of London Regiment) resting in the square at Mons 22 August 1914, the day before the Battle of Mons
A British trench near the Albert-Bapaume road at Ovillers-la-Boisselle, July 1916 during the Battle of the Somme. The men are from A Company, 11th Battalion, The Cheshire Regiment
The front line in 1916, British gains during the battle of the Somme are shaded blue.
The French, British, Belgian and American lines of attack, during the Hundred Days Offensive