and three associates were flown from the American Zone of Occupation in Germany to the US, to become spymasters for the Western Allies. In July 1946, the US officially released Gehlen and returned him to occupied Germany. On 6 December 1946, he began espionage operations against the Soviet Union, by establishing what was known to US intelligence as the Gehlen Organisation or "the Org", a secret intelligence service composed of former intelligence officers of the Wehrmacht and members of the SS and the SD, which was headquartered first at Oberursel, near Frankfurt, then at Pullach, near Munich. The organisation's cover-name was the South German Industrial Development Organization. Gehlen initially selected 350 ex-Wehrmacht military intelligence officers as his staff; eventually, the organisation recruited some 4,000 anticommunist secret agents. Gehlen Organisation, 1947–56 After he started working for the U.S. Government, Gehlen was subordinate to US Army G-2 (Intelligence). He resented this arrangement and in 1947, the year after his Organisation was established, Gehlen arranged for a transfer to the Central Intelligence Agency (CIA). The agency kept close control of the Gehlen Organisation, because during the early years of the Cold War of 1945–91, Gehlen's agents were providing the United States Federal Government with more than 70% of its intelligence on the Soviet armed forces. Early in 1948, Gehlen Org Spymasters began receiving detailed reports from their sources throughout the Soviet Zone of covert East German remilitarization long before any West German politicians had even thought of such a thing. Further operations by the Gehlen Org produced detailed reports about Soviet construction and testing of the MiG-15 jet-propelled aircraft, which United States airmen flying F86 fighters would soon to face in aerial combat during the Korean War. Between 1947 and 1955, agents of the Gehlen Organisation also interviewed every German PoW who returned to West Germany from captivity in the Soviet Union. The network employed hundreds of former Wehrmacht and SS officers, and also recruited many agents from within the massive anti-Communist Soviet and East European refugee communities throughout Western Europe. They observed the operations of the railroad systems, airfields, and ports of the USSR, and their secret agents infiltrated the Baltic Soviet Republics and the Ukrainian SSR. Among the Org's earliest counterespionage successes was Operation Bohemia, which began in March 1948 after Bozena Hajek, the sister in law of Czechoslovak Socialist Republic military intelligence chief Captain Vojtech Jerabek, defected to the American