It was the first big Cold War test of wills between the United States and the Soviet Union that threatened to turn hot and perhaps, ignite another world war just a couple of years after Germany's surrender.
Tensions between the two former allies had been building since the end of World War II. In the aftermath of the Marshall Plan and disagreements between the Russians and the western occupying powers -- the U.S., Britain, and France -- over the future of Germany, a crisis broke out on June 24, 1948, when Soviet forces blocked Allied access to the city.
With Berlin lying about a hundred miles inside Soviet-controlled territory, the city was isolated and in danger of getting starved out. But the Allies responded immediately with an airlift to resupply Berlin with a dramatic airlift which lasted for months. The Soviets finally lifted the blockade on May 12, 1949.