British Expeditionary Force (World War II)

The British Expeditionary Force (BEF) was the contingent of the British Army sent to France in 1939 after Britain and France declared war on Nazi Germany on 3 September, beginning the Second World War. The BEF existed from 2 September 1939 when the BEF GHQ was formed until 31 May 1940, when GHQ closed down and its troops reverted to the command of Home Forces.

Source: Wikipedia — British Expeditionary Force (World War II) (CC BY-SA 4.0)