LAURENCE REES: So what’s the single best decision of consequence that a leader took in the Second World War?

DAVID REYNOLDS: Well, in terms of the way the war went, probably Hitler’s agreement to change the planning for the invasion of France in 1940 from a thrust through Belgium into a thrust through the Ardennes. Because had it been a thrust through Belgium it would have been an encounter battle between the bulk of Germany’s armoured forces and the bulk of the French armoured forces in Belgium and while there were many command and control problems with the French Army, they were not grossly inferior to the Germans in terms of tanks and things like this so the war might have gone quite differently. Instead, the fact that Germany basically defeats France in four weeks, whereas in 1914 to 18 they hadn’t managed to do so in four years, that makes the Second World War fundamentally different from the First, and it seems to me that that in many ways is the turning point of the war. From that come all the other big decisions, Hitler going East, Mussolini coming into the war which opens up the Mediterranean and the Japanese deciding that this is their big chance and moving into China and so on. This is what really makes it into a world war of a completely different type from the war of 1914-18. So I think those four weeks and that decision, that change of plan, are profoundly important.