Operation Barbarossa
In the Molotov-Ribbentrop pact of 1939 Germany and the Soviet Union agreed not to fight each other. Planning for the German surprise attack started in December 1940. The attack was to start on May 15, and its main objective was to destroy the Soviet military power. Some Nazi ideological goals were included, as were Soviet deposits of natural resources, which would be helpful to keep fighting the war against the Allies.