The Battle of Arras took place on 21 May 1940, during the Battle of France in the Second World War. Following the German invasion of the Low Countries on 10 May, French and British forces advanced into Belgium. The German campaign plan (Case Yellow) had evolved into a decoy operation in the Netherlands and Belgium, with the main effort through the Ardennes. German units crossed the Meuse without waiting for reinforcements at the Battle of Sedan. Instead of consolidating bridgeheads on the west bank of the Meuse, the Germans began an advance down the Somme river valley towards the English Channel.