Leading elements of the BEF arrive in France, September 1939 (above). Following the German invasion of Poland in 1939, the British Expeditionary Force was sent to the Franco-Belgian border. By May 1940, when the German attack began, it consisted of ten infantry divisions in three corps (I, II, and III), 1st Army Tank Brigade and a RAF detachment of about 500 aircraft, the BEF Air Component. Also in France was a separate long-range RAF force, the Advanced Air Striking Force (AASF). Commanded by General Lord Gort, although constituting only a tenth of the defending Allied force it sustained heavy losses during the German advance and most of the remainder (roughly 330,000 men) were evacuated from Dunkirk between May 26 and June 4, 1940, leaving much of their equipment behind. However, the 51st (Highland) Infantry Division was left behind at Saint-Valery-en-Caux, as it was not trapped by the Germans at the time; it surrendered along with elements of the French 10th Army later in June. The short lived second Expeditionary Force commanded by General Alan Brooke was evacuated from Western France during Operation Ariel.
Although the censor has blacked out details that might give a clue to the location of these railway wagons (below), there are the same "40 men-8 horses" wagons familiar to British soldiers of an earlier war, on the way to the British concentration area around Arras.