One side in this campaign decided to march northwards because of the Lossberg Study. This campaign was revived a year later in Operation Little Saturn, part of a continuation called Case Blue. This campaign's goal was to establish a line of demarcation stretching from Arkhangelsk to Astrakhan. Georgy Zhukov led the victors during its turning point, which came during a harsh winter. This campaign is named after a red-bearded Holy Roman Emperor, and effectively ended the Molotov-Ribbentrop Pact. It ended after the bloody Siege of Stalingrad. For 10 points, name this 1941 operation in which Hitler failed to take a nation led by Joseph Stalin.   
One side in this campaign decided to march northwards because of the Lossberg Study. This campaign was revived a year later in Operation Little Saturn, part of a continuation called Case Blue. This campaign's goal was to establish a line of demarcation stretching from Arkhangelsk to Astrakhan. Georgy Zhukov led the victors during its turning point, which came during a harsh winter. This campaign is named after a red-bearded Holy Roman Emperor, and effectively ended the Molotov-Ribbentrop Pact. It ended after the bloody Siege of Stalingrad. For 10 points, name this 1941 operation in which Hitler failed to take a nation led by Joseph Stalin.         
One side in this campaign decided to march northwards because of the Lossberg Study.
Operation Barbarossa [or Fall Barbarossa; or Case Barbarossa; or Germany's invasion of the USSR; or Hitler's invasion of Soviet Russia or similar answers before the end]  