On May 10th, 1940, the German offensive into France and the Lowlands, Fall Gelb, began. By May 26th, the French and British armies were in retreat. They made their way to the last Allied controlled port town, Dunkerque (Dunkirk).
There they would be evacuated by the Royal Navy in an operation named Dynamo. This intended on rescuing 30,000 troops but it ended up rescuing over 330,000 French, British and Belgian soldiers.
There were 500,000 soldiers at Dunkirk, with no heavy weapons or anti-aircraft. Only the RAF flying from across the channel could stop the Luftwaffe from massacring the waiting troops.
The evacuation began on May 27th...