In May 1940, German forces swept through Belgium and northern France in a blitzkrieg that cut off all communication and transport between the Allies’ northern and southern forces. The Allied armies in the north, trapped by the sea near Dunkirk, France, became surrounded. Stranded along the beaches, the Allies undertook an enormous evacuation across the English Channel to Britain, an effort called Operation Dynamo. More than 338,000 Allied troops were saved in what would later be known as the “Miracle of Dunkirk.”