How weather helped the Dunkirk evacuation

In May 1940, a year into the Second World War, the Allied forces were stranded on the northern French coast.

Following the German invasion of the Netherlands, Belgium and France, around a third of a million soldiers of the British, Belgian and French armies had been forced to retreat to the port of Dunkirk by the advancing German army.

The Allies' only hope was evacuation across the English Channel - with some help from the weather.

Operation Dynamo, as it was known, saw 20 ships of the British Navy joined by 850 "Little Ships" - privately owned boats - to make multiple trips across the Channel between 26th May and 4th June.

The waters of the Channel are notoriously treacherous, which could have posed problems for the smaller boats, but thanks to a spell of settled weather the sea remained unusually calm with little more than a light breeze.

Light easterly winds blew smoke over the beaches, screening the soldiers as they waited to be evacuated.

Cloud cover between 28th and 30th May obscured the beaches, preventing the Luftwaffe from bombing the Allied forces and their rescuers as they sailed across the Channel. Above the clouds, the Royal Air Force was able to engage the Luftwaffe in the skies.

In the week of Operation Dynamo around 338,00 soldiers were rescued.