original_query: What was the significance of the Battle of Mons in relation to the British Expeditionary Force (BEF)?
query: What was the significance of the Battle of Mons in relation to the British Expeditionary Force (BEF)?
answer: The Battle of Mons was the first major action of the BEF in World War I.  Despite being outnumbered, the BEF held the line for 48 hours, inflicting significant casualties on the Germans before a planned retreat. This demonstrated the BEF's fighting capabilities and provided a crucial moral victory, proving their effectiveness against a seemingly superior force and achieving the strategic objective of preventing the outflanking of the French Fifth Army.