<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> 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>
when did the british expeditionary force go to france
when did the british expeditionary force go to france
September 1939
September 1939