Tension had characterized the Western Allies and Soviet relationship in Berlin almost from the Second World War's end, and when the Russians took decisive moves to drive the Allies out in June 1948, no one knew whether an airlift response could succeed.

Prelude to a Blockade
 Although Franklin Roosevelt, Winston Churchil and Joseph Stalin had agreed at the February 1945 Yalta conference to divide both Germany and Berlin into zones administered by each Allied power, when push came to shove, the Soviets hemmed and hawed, using excuses about conditions in the German capital to prevent Allied access until July of that year and then declaring that Western sectors of the city would not be supplied from the Soviet zone, a significant point because the city lay 110 miles inside Russian-occupied territory. A June 29 meeting resulted in a single highway and railroad line being set aside for Western use, supplemented by a November 30 agreement by the Allied Control Council (ACC) representing all four powers that granted the West three 20-mile wide air corridors to the city.

The Currency Issue
 After communist candidates decisively lost city elections in October 1946, the Soviet position grew more belligerent. They refused to allow Berlin's elected mayor, Ernst Reuter, to take office, and in early 1948 they began to harass Allied land convoys, demanding inspections that American commander Lucius CLay refused to grant. The flashpoint for the crisis became currency reform, specifically the Western plan to introduce a new deutschmark in Berlin that June. The Soviets refused to agree and introduced their own currency in response. Then, just before midnight on June 23, the day the Western deutschmark hit the streets, the Soviets cut electric power to West Berlin. On June 24, the Soviets halted all land and water access to the city; the blockade had begun.

The Airlift Begins
 Despite having run a mini-airlift to re-supply the American garrison for ten days in April, Clay was in no position to feed Berlin from the air. The United States Air Force had only 102 transport planes in all of Europe, and these C-47s, nicknamed "Gooney-Birds," could only carry three tons each. Berliners needed a minimum of 4,500 tons every day, and they currently had only about a month's extra food rations in the city and 45 days of coal. Furthermore, West Berlin had only two airports, and both needed improvements. But even though he thought the effort would fail, Clay set the airlift (named "Operation Vittles") in motion on June 26, with 32 flights delivering some 80 tons of supplies. The British, the airlift's strongest advocates, began their own "Operation Plainfare" two days later. And both the number of aircraft and the tonnage delivered began to increase.

 On July 20, the day Clay flew to Washington to consult with President Harry Truman, 2,250 tons were airlifted in to Berlin, and more than 50 larger capacity C-54s had joined the fleet. But that was still only half what Berlin required, and Clay told Truman he needed upwards of a hundred more C-54s. Truman's military advisers balked, but the president overruled them, and by early August four more squadrons of C-54s had arrived in Germany. On August 12, the U.S. and Britain combined ran 707 flights into Berlin and broke the 4,500 threshold for the first time. The airlift was well underway, and the arrival of General William Tunner as its new operational head had resulted in a number of improvements designed to maximize efficiency. But the notoriously fierce German winter had yet to make an appearance; that might prove the airlift's toughest test.