 Complete the following phrase:  Under the command of Field Marshal Sir John French, the British Expeditionary Force BEF began to deploy to France within days of the declaration of war. The first encounter with the Germans came at Mons on 23 August 1914, after which the Allies began the Great Retreat, the BEF was involved in the Battle of Le Cateau. The BEF had a small role in halting the German advance at the First Battle of the Marne, before participating in the 