Operation Barbarossa--as this campaign is famously called--was arguably the greatest land campaign mankind has ever fought. Hitler named his assault after the 12th-century Frederick I Barbarossa, an emperor of the First Reich. Although he succeeded in capturing almost 40 percent of European Russia, Hitler was defeated there. Exploiting newly available Soviet archives, David M. Glantz challenges the time-honored explanation that poor weather, bad terrain, and Hitler's faulty strategic judgement produced the German defeat. He reveals how and why the Red Army thwarted Hitler's seemingly inexorable progress.