Dunkirk is remembered for the safe evacuation of hundreds of thousands of British troops who had been cornered by German forces, but things could have been very different.

British and French soldiers had failed to halt the German advance and retreated to the port in Northern France, separated from the rest of the French army.

The troops, who had fled without much of their heavy equipment, could have been been slaughtered, but the German troops were ordered to wait.

The decision gave a vital window of opportunity for British soldiers to be rescued across the Channel.

There would not have been enough capacity if only military ships had been used and the large craft would also have struggled to get close to the beach in shallow water.

The solution was to use private yachts and pleasure boats when the call for an emergency evacuation was given on May 26, 1940.

A 10-day evacuation, named Operation Dynamo, brought around 338,000 British and French troops back to England between May 27 and June 4, 1940.

The Royal Navy sent 220 light warships and 650 other vessels under a hail of bombs and artillery fire.

Survivors described bodies floating in the water around them.

Prime Minister Winston Churchill admitted to MPs that he expected only about 20,000 or 30,000 servicemen would be saved and praised all those involved in the mammoth rescue effort.

He also warned that Hitler had a plan to invade the British Isles and said the troops would be vital to resist any invasion.