Sam's guest this week is the broadcaster and historian Jonathan Dimbleby. In Barbarossa: Hitler's Greatest Mistake, Jonathan describes the extraordinary and horrifying story of the Nazi campaign against Stalin, and its still more extraordinary strategic and diplomatic background. It's a bloody and sometimes tragicomic parable of how dictators can become detached from reality - and in it he makes the case that, contra the prevailing image of Anglo-American victories in France having been decisive in winning the Second World War, Hitler's goose was actually cooked as early as 1941.