In June 1948, the Soviet Union blockaded all rail, road, and canal access to West Berlin, which was located deep inside the Soviet-occupied zone of Germany. The aim of the blockade was to force the Western Allies (the United States, Britain, and France) to withdraw from West Berlin and allow the city to be incorporated into East Germany.
In response, the Western Allies launched a massive airlift operation, known as the Berlin Airlift, to supply West Berlin with food, fuel, and other essential goods. The airlift was a success, and it continued for nearly a year until the Soviet Union finally lifted the blockade in May 1949.
The Berlin Airlift was a major victory for the Western Allies and it helped to preserve West Berlin's freedom and democracy. It also showed that the Western Allies were willing to stand up to Soviet aggression and defend the interests of their allies.