From May 26 to Jun. 4, 1940, one of the largest evacuations in human history saved approximately 338,000 Allied troops at Dunkirk and gave the Allies the strength to continue resisting Adolph Hitler's Third Reich. The "Miracle at Dunkirk" was more successful than the planners' wildest dreams, partially because of the skill and bravery of boat crews and troops but also because of horrible decisions by the German high command.
The days leading up to the evacuation were characterized by one of the most effective German Blitzkriegs. British, Belgian, and French forces were falling back across France and a thrust by Germany through the Ardennes successfully cut the Allied force in half. By May 19, Britain was looking for ways to get its expeditionary force back across the channel.
A failed counterattack on May 21 sealed France's fate but Germany's advances made it appear impossible to stage a large evacuation. The Germans crossed the canals near Dunkirk by May 24 and were about to capture Dunkirk, the last port the British could feasibly use. Luckily, Hitler ordered his Panzers to stop advancing and to even fall back a short distance to the canals.
Hitler's reasoning is a source of debate, but two main factors are thought to have been uppermost in his mind.
First, Hermann Goering may have been successful in his attempts to convince the fuhrer that the Luftwaffe could kill the troops on the beaches of Dunkirk . Also, there was a chance that Hitler believed that Britain was more likely to surrender if it hadn't been embarrassed and didn't have the slaughter of approximately 200,000 of its own troops to rally around.
Unfortunately for Hitler, Britain sent nearly the entirety of the Royal Air Force, including planes from the defensive-in-nature British Metropolitan Air Force, to cover Operation Dynamo. Working with French and British navy ships in the waters below, they were able to establish a weak air superiority over the beaches and parts of the channel, limiting the chances for the Luftwaffe to attack.
On May 25, King George VI declared a national day of prayer and attended a special service at Westminster Abbey. The next day, Operation Dynamo kicked off. Almost 400,000 British, Belgian, and French troops lined up in the water and on the beaches in hopes of rescue. Senior commanders were skeptical that they could get even 25 percent of them to safety.
In a perimeter around Dunkirk, British and French units prepared to fight delaying actions, often to the last man, to give their buddies a chance to retreat. On May 26, these troops were sorely tested. The Belgian King Leopold, whose troops were cut off in small pockets and being quickly overwhelmed, surrendered and Hitler allowed the Panzers to attack Dunkirk.
As the tanks crashed against the defenders, the Royal Air Force and other planes desperately fought to keep the Germans away from the ships. The Royal Navy was attempting to evacuate as many men as possible, but found itself unable to keep up.
British leaders finally announced to the public how desperate the situation on the beaches was. Dunkirk was burning to the ground and troops were being bombed on the sand and strafed as they stood neck-deep in the water. The public responded valiantly, cobbling together hundreds of privately-owned vessels to form a flotilla of "Little Ships" that became a symbol of British perseverance.
The action drug on for days as six destroyers, eight personnel ships, and about 200 small craft were sunk and tens of thousands of men were killed or captured. But, 338,000 troops were rescued, approximately 140,000 from the British Expeditionary Force and 198,000 from the Polish, French, and Belgian armies. Forty-thousand were lost, either captured or killed.
In Britain, "Dunkirk Spirit" became a symbol of national pride, an embodiment of how Britons could come together to face down any foe and overcome any challenge. Prime Minister Winston Churchill spoke in the House of Commons, saying that Britain would fight on the beaches, on the landing grounds, in the fields, and in the streets.