Allied forces retreated from the German advance through north-western Europe, and fell back to the Channel ports of France where they were trapped. Their rescue was codenamed Operation Dynamo and, against all odds, thousands of men were dramatically evacuated in the "miracle of Dunkirk".
Photo: British soldiers shoot at attacking aircraft during the evacuation, June 1940. (Getty Images)
The crises facing Churchill.
A defiant Churchill's cabinet implodes over Hitler's peace offer and the British Expeditionary Force retreats to Dunkirk. King George VI calls for a national day of prayer as Britain stands alone against the Nazis.
Lt Gen Sir Brian Horrocks, who commanded a battalion at Dunkirk, describes the lead up to the Dunkirk evacuation.
In the month after the Suez crisis and the Hungarian revolution, Lt Gen Sir Brian Horrocks, who commanded a battalion at Dunkirk, expertly illustrates how the German forces encircled the British troops at Dunkirk.
British forces are evacuated from Dunkirk.
Richard Holmes describes how Churchill took the "astonishingly risky" decision to evacuate British troops from Dunkirk. Holmes suggests that this was part of the same indomitable spirit that led Churchill to declare that he would die for his country before he surrendered.
Andrew Marr traces the journey of the little ships
Andrew Marr describes how, under attack from the Luftwaffe, the heroic sailors of the little ships rescued thousands of trapped, retreating soldiers from the chaos of Dunkirk.
The triumph of Dunkirk
On the 27th May 1940, the order is given to "evacuate the maximum force possible" from the beaches of Dunkirk. RAF fighters join forces with Royal Navy destroyers and boats of every kind to bring the troops back to Britain.
Operation Dynamo - the evacuation begins
In May 1940, Germany invaded Belgium, the Netherlands, Luxembourg and France. French and British forces fell back in the face of the rapid German advance and thousands of Allied troops retreated to the French Channel ports, particularly Dunkirk.
Faced with the annihilation or capture of their army, the British government launched Operation Dynamo to evacuate as many British troops as possible. French soldiers were later included in the evacuation. The operation officially began on 26 May, lasting until 4 June. It was co-ordinated from Dover Castle by Vice Admiral Bertram Ramsay. His headquarters were in a room which had once held an electrical dynamo, hence the operation's name.
The little ships
The British government appealed to the owners of small boats to sail across to Dunkirk to help with the rescue. About 850 "little ships" answered the call, either ferrying men from the beaches to naval vessels waiting offshore, or taking soldiers straight back to England.
The Luftwaffe launched repeated attacks on the evacuation ships and the men onshore. Although heavily outnumbered, the RAF made a huge contribution to fighting off these attacks. The British evacuation was also aided on 24 May by Hitler's surprising decision to halt their advance on Dunkirk for 48 hours.
338,000 men rescued
The exact figures of those rescued vary, but the British Admiralty calculated that 338,000 men were evacuated. Two thirds of them were British, and the remainder were largely French with some Polish and Belgian troops. However, all their heavy equipment and vehicles were left behind on the beaches or destroyed on the roads into the town.
British and French troops were left behind to defend the Dunkirk perimeter. They faced either death or an uncertain future as prisoners of war. About 34,000 British soldiers were taken prisoner in and around the town.
"We shall never surrender!"
The escape of so many from Dunkirk, as well as smaller numbers from Le Havre, Cherbourg and other ports, was a huge boost to morale in Britain. Dunkirk came to be regarded as a victory rather than a defeat. Churchill acknowledged this, but tempered it by saying: "Wars are not won by evacuations".
In the same impassioned speech, given to the House of Commons on 4 June 1940, he declared Britain faced a life or death struggle against Germany and decreed that "We shall fight on the beaches, we shall fight on the landing grounds, we shall fight in the fields and in the streets, we shall fight in the hills. We shall never surrender!".