<P> The British Expeditionary Force (BEF) was the name of the British Army in Western Europe from 1939 to 1940 during the Second World War . In the 1930s, the British government had planned to deter war by rearming from the very low level of readiness of the early 1930s . The first step was the abolition of the Ten Year Rule but the bulk of the extra money went to the Royal Navy and the Royal Air Force (RAF). Plans had been made to re-equip a small number of Regular and Territorial divisions, potentially for service overseas . </P> <P> The BEF had been established in 1938, in readiness for war, after Nazi Germany annexed Austria in the Anschluss of March 1938 and made claims on Sudetenland in Czechoslovakia, that led to the Munich Agreement (30 September 1938). The French and British governments forced the Czechoslovak government into ceding Sudetenland to Germany; the German occupation of Czechoslovakia took place on 15 March 1939 . After the French and British governments had undertaken in the Franco - Polish Military Alliance to defend Polish independence, the German invasion of Poland began on 1 September; on 3 September, after the expiry of an ultimatum, the British and French declaration of war on Germany was promulgated . </P> <P> The BEF (General Lord Gort) began moving to France in September 1939 . The British assembled along the Belgian--French border on the left of the French First Army as part of the French 1er groupe d'armées (1st Army Group) of the Front du Nord - est (North - Eastern Front). Most of the BEF spent the Phoney War digging field defences on the French--Belgian border, before the Battle of France (Fall Gelb) began on 10 May 1940 . The BEF constituted 10 percent of the Allied forces on the Western Front . The BEF participated in the Dyle Plan, a rapid advance into Belgium to the line of the river Dyle but had to retreat through Belgium and north - western France with the rest of the 1er groupe d'armées, after the German breakthrough further south at the Battle of Sedan . The BEF, French and Belgian forces cut off north of the Somme river were evacuated from the French North Sea coast through port and beaches of Dunkirk in Operation Dynamo . </P> <P> Saar Force, the 51st (Highland) Infantry Division and attached units, had been transferred from the BEF for service along the Maginot Line, as part of a plan for the BEF units to gain experience . The force fought with local French units until the German offensive began, then moved west to join the Tenth Army along the Channel coast, joining the Beauman Division improvised from troops on the lines - or - communications and the 1st Armoured Division from England, to fight in the Battle of Abbeville (27 May--4 June) south of the Somme . The British government was attempting to re-build the BEF, with divisions training in Britain, troops from France and the lines - or - communications troops south of the Somme river (informally known as the 2nd BEF). After the success of the second German offensive in France (Fall Rot) over the Somme and Aisne rivers, British troops were evacuated from Le Havre in Operation Cycle (10--13 June) and the French Atlantic and Mediterranean ports in Operation Ariel (15--25 June, unofficially to 14 August). </P>

When did the british expeditionary force go to france