The Bizone or Bizonia was the combination of the American and the British occupation zones in 1947 during the occupation of Germany after World War II. With the addition of the French occupation zone on the first of June 1948 the entity became the Trizone (sometimes jokingly called Trizonesia, as, for example, in a well-known Karneval song from that time, the Trizonesien-Song). Later, on 23 May 1949, the Trizone became the Federal Republic of Germany, commonly known as West Germany.
The Soviet Union, which encouraged and partly carried out the post-war expulsions of Germans from the areas under its rule, stopped delivering agricultural products from its zone in Germany to the more industrial western zones, thereby failing to fulfill its obligations under the Potsdam Agreements to provide supplies for the expellees, whose possessions had been confiscated. At Potsdam, it had been agreed that 15% of all equipment dismantled in the Western zones — especially from the metallurgical, chemical, and machine manufacturing industries — would be transferred to the Soviets in return for food, coal, potash (a basic material for fertilisers), timber, clay products, petroleum products, etc. The Western deliveries had started in 1946.
The Soviet deliveries — desperately needed to provide the eastern expellees with food, heat, and basic necessities, and to increase agricultural production in the remaining cultivation area — did not materialise. Consequently, the American military administrator, Lucius D. Clay, stopped the transfer of supplies and dismantled factories from the Ruhr area to the Soviet sector on 3 May 1946 while the expellees from the areas under Soviet rule were deported to the West until the end of 1948. As a result of the halt of deliveries from the western zones, the Soviet Union started a public relations campaign against American policy and began to obstruct the administrative work of all four zones.