"Approaching this place, soldiers used to say: 'We are entering hell.' And after spending one or two days here, they say: 'No, this isn't hell, this is ten times worse than hell.'" - Soviet general Vasily Chuikov
World War II was fought on a scale unlike anything before or since in human history, and the unfathomable casualty counts are attributable in large measure to the carnage inflicted between Nazi Germany and the Soviet Union during Hitler's invasion of Russia and Stalin's desperate defense. The invasion came in 1941 following a nonaggression pact signed between the two in 1939, which allowed Hitler to focus his attention on the west without having to worry about an attack from the eastern front. While Germany was focusing on the west, the Soviet Union sent large contingents of troops to the border region between the two countries, and Stalin's plan to take territory in Poland and the Baltic States angered Hitler. By 1940, Hitler viewed Stalin as a major threat and had made the decision to invade Russia: "In the course of this contest, Russia must be disposed of...Spring 1941. The quicker we smash Russia the better." (Hoyt, p. 17)
The surprise achieved by the German invasion in 1941 allowed their armies to advance rapidly across an incredibly wide front, but once winter set in, the two sides had to dig in and brace for German sieges of Russian cities. In the spring of 1942, Germany once more made inroads toward Stalingrad, Stalin's own pet city. Not surprisingly, he ordered that it be held no matter what. There was more than vanity at stake though. Stalingrad was all that stood between Hitler and Moscow.