What was the Berlin Wall and the Berlin blockade?
The Berlin blockade was initiated by the Soviets in June of 1948 response to the American decision to merge all of the Allied zones of Berlin and the western part of Germany into one, and to begin setting up a government along western lines for the new state. The Soviets responded by blockading all roads into West Berlin, which was actually located in East Germany. Faced with the possibility of war, the Allies rendered the blockade ineffective through a massive effort known as the Berlin Airlift, in which thousands of American and British planes dropped tons of supplies into the sealed-off city. The Soviets lifted the blockade in May of 1949.
The Berlin Wall was built much later, in response to the massive outflow of East German immigrants into West Berlin. It came as the culmination to a strategic move by Nikita Khrushchev to consolidate control of East Berlin, which had previously been disputed by the Americans, into the hands of East Germany. Embarrassed at the loss of literally hundreds of thousands of East German citizens, Khruschev ordered that the border be closed in the summer of 1961. Eventually the Berlin Wall was built, encircling the entire Western half of the city, separating it from East Berlin and East Germany in general.