Operation Barbarossa, Hitler's invasion of the Soviet Union in 1941, led to one of the most brutal campaigns of World War II: of the estimated 70 million people who died in the war, over 30 million died on the Eastern Front. Although it has previously been argued that the campaign was a pre-emptive strike, in fact, Hitler had been planning a war of intervention against the USSR ever since he came to power in 1933. Using previously unseen sources, acclaimed military historian Rolf-Dieter Muller shows that Hitler and the Wehrmacht had begun to negotiate with Poland and had even considered an...