The British Expeditionary Force and some French troops were trapped in a pocket around the port of Dunkirk. On 16th May 1940 at 18:57, Operation Dynamo began. Over the next 9 days, the sea was leaden and calm, unusual for the Channel. The Royal Navy sent an armada ranging from small motor launches to destroyers across the Channel to ferry back the Allied troops. The calm sea allowed them to be brought across the sands & heavy overcast sky prevented effective Luftwaffe attacks.
