Following the fall of Nazism in 1945, Germany was divided up between four major authorities:

• United States,
• Britain,
• France,
• Soviet Union.

At the Potsdam Conference in August 1945, after Germany's unconditional surrender on May 8, 1945, the Allies divided Germany into four military occupation zones – French in the southwest, British in the northwest, United States in the south, and Soviet in the east. The territories east of the Oder-Neisse line (East Prussia, Eastern Pomerania and Silesia) were removed from Germany and put under Soviet and Polish administration, effectively shifting Poland westward; this administration was originally intended to last until a final peace treaty was to be signed, which however did not happen until 1990. A transfer of Germans from Poland, Czechoslovakia and Hungary was agreed on, but the countries were urged to stop the expulsions of these Heimatvertriebene.

The intended governing body was called the Allied Control Council. The commanders-in-chief exercised supreme authority in their respective zones and acted in concert on questions affecting the whole country. Berlin, which lay in the Soviet sector, was also divided into four sectors.

The United States, the United Kingdom, and the Soviet Union had agreed at Potsdam to a broad program of decentralization, treating Germany as a single economic unit with some central administrative departments. These plans broke down in 1948 with the emergence of the Cold War. The Western powers were concerned about the deterioating economic situation in their zones; the American Marshall Plan economic aid was extended to Western Germany and a currency reform introduced the Deutsche Mark and halted rampant inflation there. The Soviets had not agreed to this currency reform and withdrew in March 1948 from the four-power governing bodies and initiated the Berlin blockade in June 1948, blocking all ground transport routes between the FRG and Berlin. The western allies replied with a continuous airlift of supplies to the western half of the city. The Soviets ended the blockade after 15 months.

In 1949, the Western occupied zones were established as the Federal Republic of Germany (FRG, Bundesrepublik Deutschland, or West Germany). The Soviet Zone became the German Democratic Republic (GDR, Deutsche Demokratische Republik, or East Germany). Also in 1949, on September 6, Allied military authorities relinquished control of former Nazi Germany assets back to German control. This division endured as a troubled cooperation until a Soviet walkout in Berlin in 1948 which fractured occupied Germany and initiated the Cold War.

Only two jointly-run four-power organizations survived the division of Germany. Both were in West Berlin, Germany, and existed during the Cold War from 1948 to 1989. These were the Berlin Air Safety Center and Spandau Prison.

These two organizations were uniquely four-powered in that American, British, French, and Soviet authorities cooperated together in their management (see Four-Power Authorities). This was a far cry from the intense adversarial relationship the allies had with the Warsaw Pact leader on every other aspect of world affairs during this timeframe.

Both organizations remained low-profile and secretive during their existences to avoid highlighting the politically sensitive nature of their interactions and cooperations.

See also History of Germany since 1945.