In the later part of World War II, Germany was at a logistical disadvantage, having failed to conquer the USSR with Operation Barbarossa (June–December 1941), and its drive for the Caucasus (June 1942–February 1943). The failed conquest had depleted German resources, and its military-industrial complex was unprepared to defend the Greater Germanic Reich against the Red Army's westward counterattack. By early 1943, the German government began recalling from combat a number of scientists, engineers, and technicians; they returned to work in research and development to bolster German defense for a protracted war with the USSR. The recall from frontline combat included 4,000 rocketeers returned to Peenemünde, in northeast coastal Germany.