‘Lenin left a state and we’ve fucked it up,’ said Stalin, returning to his mansion for two days to collect himself and, like Ivan the Terrible, test the loyalty of his boyars. On the third, his grandees arrived to insist that he take command. The Georgian ex-choirboy who, like Hitler, believed he was a born soldier, assumed the title Supremo and, mustering Russia’s unparalleled resources of human and industrial power, fielding an awesome 4.2 million troops, rallied his own people with a mix of patriotism, terror and Marxism to engage Hitler in a ‘life-and-death struggle’.