 In the middle of 1940 , following the rising tension between the Soviet Union and Germany over territories in the Balkans , an eventual invasion of the Soviet Union seemed to Hitler to be the only solution . While no concrete plans were made yet , Hitler told one of his generals in June that the victories in Western Europe finally freed his hands for his important real task : the showdown with Bolshevism . With the successful end to the campaign in France , General Erich Marcks was assigned to the working group drawing up the initial invasion plans of the Soviet Union . The first battle plans were entitled Operation Draft East ( but colloquially it was known as the Marcks Plan ) . His report advocated the A @-@ A line to be the operational objective of any invasion of the Soviet Union . This goal would extend from northern city of Arkhangelsk on the Arctic Sea through Gorky and Rostov to the port city of Astrakhan at the mouth of the Volga on the Caspian Sea . The report concluded that this military border would reduce the threat to Germany ( and the Third Reich ) from attacks by enemy bombers . 
