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).
The term British Expeditionary Force is often used to refer only to the forces present in France prior to the end of the First Battle of Ypres on 22 November 1914. By the end of 1914—after the battles of Mons, Le Cateau, the Aisne and Ypres—the existent BEF had been almost exhausted, although it helped stop the German advance. An alternative endpoint of the BEF was 26 December 1914, when it was divided into the First and Second Armies (a Third, Fourth and Fifth being created later in the war). "British Expeditionary Force" remained the official name of the British armies in France and Flanders throughout the First World War.
Emperor Wilhelm II of Germany, who was famously dismissive of the BEF, allegedly issued an order on 19 August 1914 to "exterminate ... the treacherous English and walk over General French's contemptible little army". Hence, in later years, the survivors of the regular army dubbed themselves "The Old Contemptibles". No evidence of any such order being issued by the Kaiser has ever been found.
Formation
Under the terms of the Entente Cordiale the United Kingdom had a diplomatic "understanding" with France to counter military aggression from the German Empire in the European continent. Detailed plans had been drawn up in advance for the British Army in the event of war breaking out between those two countries to dispatch a "British Expeditionary Force" to France which consisted of six infantry divisions and five cavalry brigades under the command of General Sir John French to repel any German attack in the West. The BEF was arranged into I Corps, under the command of General Sir Douglas Haig, and II Corps, under the command of General Sir James Grierson, which embarked for France on 15 August 1914.
In October 1914, 7th Division arrived in France, forming the basis of III Corps and the cavalry had grown to form the Cavalry Corps of three divisions. By December 1914, the BEF had expanded to such an extent that the First Army and the Second Army were formed.
By the end of 1914, after the battles of Mons, Le Cateau, the Aisne and Ypres, the old regular British Army had suffered massive casualties and lost most of its fighting strength but had managed to help stop the German advance.
Command structure
The force was commanded by Field Marshal Sir John French until December 1915, when he was replaced by General Sir Douglas Haig. The BEF's Chief of Staff on mobilisation was General Archibald Murray. He was replaced in January 1915 by General William Robertson. Lieutenant-General Launcelot Kiggell then served as Chief of Staff from December 1915 to January 1917 when he was succeeded by Lieutenant-General Herbert Lawrence. The first two Corps were commanded by Haig (I Corps) and Horace Smith-Dorrien (II Corps).
Kitchener's New Army
As the Regular Army's strength declined, the numbers were made up, first by the Territorial Force, then by volunteers from Field Marshal Kitchener's New Army.By the end of August 1914, he had raised six new divisions and by March 1915, the number of divisions had increased to 29. The Territorial Force was also expanded, raising second and third line battalions and forming eight new divisions, which supplemented its peacetime strength of 14 divisions. The Third Army was formed in July 1915 and with the influx of troops from Kitchener's volunteers and further reorganisation, the Fourth Army and the Reserve Army, became the Fifth Army in 1916.