From May 26 to June 4, 1940, the evacuation of Allied troops from the French port of Dunkirk and its surrounding beaches, known as Operation Dynamo, was a hugely important event in the history of World War II. Had Dynamo not succeeded, Winston Churchill, who had come to power only 16 days before Dynamo began, would almost certainly have lost his premiership, and been dismissed as a dangerous fantasist and warmonger, and the British government forced to negotiate an armistice with Germany. In the event, the evacuation turned out to be a success beyond even the wildest dreams of its most enthusiastic promoters, who had hoped to rescue at most 45,000 troops but by the end of the 10-day exercise had plucked more than 300,000 soldiers from the piers and beaches of Dunkirk—including, as it happens, my father, then a very green 21-year-old second lieutenant in the Royal Artillery, who, less than a year before, had been a failed teacher in a state elementary school west of Birmingham in the Black Country.
Dynamo was first and foremost an intricate and complex naval operation in which each new day’s tactics had to be spontaneously improvised, with every day expected to be the last. The beaches that extend east and west of Dunkirk are very shallow and gently shelving, but the ships capable of carrying large numbers of soldiers, from passenger ferries to naval destroyers, were deep-drafted, needing at least 14 feet and more to stay afloat. So fleets of much smaller boats, drawing four feet six inches or less, were needed to bridge the gap between the lines of wading troops, standing up to their shoulders in cold seawater (about as cold as Puget Sound in May), and the ships that would bring them back to England, just over 25 nautical miles across the channel.