The Second World War had already been in progress for nearly two years when Hitler's armies broke a peace pact with the Soviet Union and invaded it in the summer of 1941. The German army was both well-equipped and well-led, while the Soviets, believing in Hitler’s good faith and ill-prepared for war, were taken by surprise.
The Nazis quickly scored a series of incredible victories. By the end of 1941 Hitler's soldiers they had laid siege to Leningrad (now renamed St Petersburg) in the north and reached the suburbs of the capital, Moscow. Stalin, the leader of the Soviet Union, was a hair's-breadth from defeat. More than three million Russians had been taken prisoner and another million were dead.
As the winter fighting died down, both sides settled into an uneasy truce while preparations were made for summer campaigns. Hitler believed that one more push in 1942 would see the end of the USSR and give Germany a gigantic new empire in eastern Europe - ‘our India’ as he dubbed it. The Russian people would be enslaved or wiped out; he dreamed of levelling Moscow and constructing a great lake on its ruins.
Stalin was determined to repel the invaders. He began preparations against a German assault on Moscow but, much to his surprise, it never took place.
Instead, Hitler decided to unleash his armies to the south and capture the Soviet Union's vital oil reserves in Baku.
Before this could be accomplished, though the heavily garrisoned city of Stalingrad, situated on the banks of the river Volga, would have to be captured.