The British Expeditionary Force (BEF) was the part of the British Army in Europe from 1939 to 1940, early in the Second World War. Commanded by General Lord Gort, the BEF constituted 10 percent of the Allied force.
The British Expeditionary Force was established in 1938, in readiness for war, after Germany annexed Austria in the Anschluss of March 1938 and made claims on Sudetenland, that led to the invasion and German occupation of Czechoslovakia in March 1939. After the French and British government had promised to defend Poland, the German Invasion of Poland began on 1 September and on 3 September, Britain and France declared war on Germany.
The BEF went to France in September 1939 and mostly assembled along the Belgian–French border during the Phoney War before May 1940. The BEF did not commence hostilities until the German invasion that began the Battle of France on 10 May 1940. The BEF was driven back through Belgium and north-western France, forcing its evacuation from several ports along the French northern coastline in Operation Dynamo, followed by Operation Cycle, an evacuation from Le Havre and Operation Ariel, evacuations from the French Atlantic and Mediterranean ports. The most notable evacuation was from Dunkirk and from this the phrase Dunkirk Spirit was coined.
