The original blitzkrieg invasion plan, which the Axis called Operation Barbarossa, had called for the capture of Moscow within three to four months. However, despite large initial advances, the Wehrmacht was soon slowed by Soviet resistance (in particular during the Battle of Smolensk, which lasted from July through September 1941 and delayed the German offensive towards Moscow for two months). Having secured Smolensk, the Wehrmacht was forced to consolidate its lines around Leningrad and Kiev, further delaying the drive towards Moscow. The Axis advance was finally renewed on September 30, 1941, with an offensive codenamed Operation Typhoon, the goal of which was the capture of Moscow before the onset of winter.