The name given to British troops deployed for immediate conflict in the first half of the twentieth century. As a result of Haldane's army reforms in 1906–7, a territorial reserve army was created in Britain, and it was advised that this, along with the regular army, should be made ready for dispatch overseas in an emergency. When World War I was declared on 4 August 1914, both regular and reserve troops were sent to France under Sir John French, as the BEF. As German troops advanced into France, the BEF moved up the German flank towards Belgium, before it was defeated at the Battle of Mons (23–4 August). After a steady retreat, it took part in the first Battle of Ypres (20 October–17 November). Estimates suggest that by the end of November, survivors from the original force averaged no more than one officer and thirty men, in each battalion of about 600 men.
In World War II, an expeditionary force was again mobilized and sent to France in September 1939, as Britain's contribution to its alliance with France. It comprised 152,000 men and, from 4 September, was situated along the Belgian border. By May 1940, it numbered 394,165 men, and was also stationed along the Franco‐German border. On 10 May, when Germany attacked, the BEF moved towards Belgium, but was soon forced to withdraw from Dunkirk. A number of other evacuations took place in May and June, leaving behind 64,000 vehicles and other important equipment. Altogether, it lost 68,111 killed, wounded, or captured.
Subjects: Second World War — Contemporary History (Post 1945).