May 27 - June 4, 1940. The Dunkirk Evacuation. In May, 1940, British and French troops were stranded on the beaches of Dunkirk, pushed back to the English Channel by German forces. A rescue mission -- Operation Dynamo -- involved around 700 small boats, all crewed by volunteers, ferrying men to larger ships that took them across the channel. 338,000 soldiers were rescued.