The end of World War II in 1945 saw Germany divided into four Allied occupation zones. Berlin, the German capital, was likewise divided into occupation sectors, even though it was located deep within the Soviet zone. The future of Germany and Berlin was a major sticking point in postwar treaty talks, and tensions grew when the United States, Britain, and France moved in 1948 to unite their occupation zones into a single autonomous entity–the Federal Republic of Germany (West Germany). In response, the USSR launched a land blockade of West Berlin in an effort to force the West to abandon the city. However, a massive airlift by Britain and the United States kept West Berlin supplied with food and fuel, and in May 1949 the Soviets ended the defeated blockade. By 1961, Cold War tensions over Berlin were running high again. For East Germans dissatisfied with life under the communist system, West Berlin was a gateway to the democratic West. Between 1949 and 1961, some 2.5 million East Germans fled from East to West Germany, most via West Berlin. By August 1961, an average of 2,000 East Germans were crossing into the West every day. On August 15, 1961, East German workers began construction of the Berlin Wall. For the next 28 years, the heavily fortified Berlin Wall stood as the most tangible symbol of the Cold War–a literal “iron curtain” dividing Europe.