The Cold War began after World War II as relations between the United States and the Soviet Union deteriorated. The two countries competed for influence around the world, and Germany became a major battleground in this competition. The division of Berlin became a symbol of the division of Germany and Europe, and the Berlin Wall became a physical manifestation of the Cold War.
In June 1948, the three western sectors of Berlin were combined to form an autonomous city called West Berlin, while the Soviet sector became known as East Berlin. Despite the division of the city, the residents of West Berlin could still travel freely to East Berlin and the rest of East Germany.
The situation changed in August 1961, when the government of East Germany began building the Berlin Wall. The wall was constructed to prevent people from West Berlin from crossing into East Berlin, and it became a symbol of the oppression and repression of the communist government in East Germany.
The Berlin Wall stood for 28 years, until it was finally demolished in 1989. The fall of the Berlin Wall is considered a major turning point in the Cold War, and it played a significant role in the reunification of Germany.