It's known as the Miracle of Dunkirk: in May 1940, approximately 340,000 Allied troops were trapped with their backs to the sea. Sitting ducks, the troops were subjected to an endless barrage of bombs and bullets as the Luftwaffe apparently bombed at will. The situation seemed hopeless. Then a fleet of ships appeared on the horizon, mostly sent by the Royal Navy but joined by smaller craft captained by plucky civilians. The soldiers were rescued from the beaches and taken safely back to Britain. They would later return to win the war. But behind the Miracle of Dunkirk there's another, hidden story. Soldiers and mariners, angry that they'd apparently been left undefended against the Luftwaffe, blamed the RAF. Historians have long viewed Dunkirk as the RAF's poorest hour. But now, recently released MoD files reveal that, far from being absent, the RAF were suffering massive losses supporting the evacuation.