The hot movie of the moment is Christopher Nolan's Dunkirk, which retells the story of the evacuation of allied troops from the French city of that name during World War II. But this was an epic evacuation, with more than 333,000 mostly British and French soldiers rescued from the beachhead. In fact, had the Germans opted to attack instead of holding back, such a decisive win in 1940 might have changed the outcome of the war, writes James Gibney at Bloomberg. (The headline says Germany "blew it.") So why didn't they? All these years later, the answer remains unclear, says historian Robert Citino. He recounts the confusion among Hitler and his top Panzer commanders and says one thing is clear: The Germans realized their mistake almost immediately, even as the evacuation was taking place. Read the full Q&A here. Related stories: