Foreign Armies East, or Fremde Heere Ost (FHO), was a Nazi German military intelligence organization that focused on analyzing the Soviet Union and other East European countries before and during the Second World War. The FHO was also tasked with the acquisition of information from Soviet POWs. See German mistreatment of Soviet prisoners of war.
Starting in 1942, it was run by Reinhard Gehlen, and employed about 35 people. Gehlen predicted the downfall of the Nazi state, and the coming Cold War between the US and the Soviet Union. He planned to preserve his office of the FHO and then present it to the US as a sort of gift. As the war ended, Gehlen hid himself, his staff and his microfilmed files in the chaos of the downfall of Hitler's government. General William Wilson Quinn of the US Seventh Army, recognized Gehlen's name from a report by Allen Dulles of the OSS. He ensured Gehlen and his material were brought to the attention of the US government.
Gehlen revealed his plan for Foreign Armies East to Captain John Boker of US Military Intelligence, who persuaded General Edwin Sibert of USFET to listen to Gehlen. The J-2 staff of the Pentagon was also involved. These operations eventually led to the formation of Operation X, Operation Rusty, 'the Organization', 'the Org', and finally, the 'Gehlen Organization'.
The Gehlen Organization became a powerful spy ring during the early years of the Cold War. Eventually, this organization was transformed into the Bundesnachrichtendienst, or BND, West Germany's intelligence service.
Many of the controversial aspects of Gehlen and his organization, such as its links to old Nazis, and its infiltration by Eastern bloc agents, were later described by Heinz Höhne & Hermann Zolling, in articles and a book, The General Was a Spy.