Clausewitz observed of Russia that "it was a country which could be subdued only by its own weakness and by the effects of internal dissension. In order to strike these vulnerable spots of its body politic, Russia would have to be agitated at the very center." In reading this study, the military student will realize how dearly the Germans had to pay for ignoring Clausewitz's advice. The purpose of this study is to describe German planning and operations in the first part of the campaign against Russia. The narrative starts with Hitler's initial plans for an invasion of Russia and ends at the time of Germany's maximum territorial gains during the battle for Stalingrad. The material for this study was obtained from Germany military records now in the custody of The Adjutant General, Department of the Army. Monographs by former German general officers who had an active part in the planning and operations provided additional information. The authors of these monographs, prepared for the Historical Division, United States Army, Europe, include Generaloberst Franz Halder, Chief of Staff of the German Army from 1938-1942; Generaloberst Gotthard Heinrici, a former corps, army, and group commander on the Russian front; and several others. The study was written by George E. Blau of the Special Studies Division, Office of the Chief of Military History. In his presentation, the author made every effort to give an objective account of Germany's initial efforts to conquer Soviet Russia in World War II.