The Battle of France, also known as the Western Campaign, the French Campaign and the Fall of France, during the Second World War, was the German invasion of France, that notably introduced tactics that are still used. France and the Low Countries were conquered, ending land operations on the Western Front until the Normandy landings on 6 June 1944.

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. During the 1930s, the British government had planned to deter war by abolishing the Ten Year Rule and rearming from the very low level of readiness of the early 1930s. The bulk of the extra money went to the Royal Navy and the Royal Air Force but plans were made to re-equip a small number of Army and Territorial Army divisions for service overseas.