LAURENCE REES: What do you see as the single greatest turning point of the war?

DAVID REYNOLDS: I think it has to be Barbarossa really. It’s this hubristic attack on the Soviet Union years ahead of when the German Wehrmacht was in a position to do it, and with no preparation for a long campaign, which if the Russians could hold on was going to completely change the character of the war. I think that would not have happened in 1941 but for the really heady sense of victory that was generated by the events of 1940, the fall of France and so on, that gave the sense that the Wehrmacht was invincible and that Hitler was a great leader.