For 49 years, Berlin, the former capital of Adolf Hitler's Nazi Germany, was occupied by the victorious allies of World War II: the United States, Great Britain, France, and the Soviet Union. In 1945, the four allies divided Berlin into four sectors of occupation, and the American, British, and French sectors quickly became known as Free Berlin. The Western Allies undertook political and economic rehabilitation of the war-ravaged city, which stood as an island surrounded by Soviet-held territory and as the only democratic community behind the Iron Curtain. By 1947, Cold War tensions had replaced wartime cooperation, and in June 1948 the Soviet Union blockaded land access to Berlin in hopes of stopping the development of a democratic West German state. The Western Allies responded with the Berlin Airlift, delivering food, fuel, and hope to more than two million West Berliners in 1948 and 1949. Although the airlift succeeded, Germany emerged divided between the democratic Federal Republic of Germany in the west and the Communist, centralized, and coercive German Democratic Republic in the east. Allied forces protected Berlin against a Communist takeover, while many disillusioned and persecuted East German citizens fled to the west through West Berlin's unguarded sector borders during the 1950s. By 1961, 3.5 million people out of a population of 17 million had left East Germany, leaving it on the brink of economic ruin. For much of this era, an ugly wall divided Berlin geographically, politically, spiritually, and economically, and until masses of people began dismantling it on November 9, 1989, it symbolized the Cold War conflict between democratic principles and communism.