With hindsight, the path that led to the twenty-fourth of June 1948 can easily be traced. On that date, the Russian government severed all land and water communications between the Western zones of Germany and Berlin, in the heart of the Soviet zone but itself divided into four. It also halted all rail and canal traffic into and out of the city and required all road traffic to take a twenty-three kilometre detour. The Foreign Secretary Ernest Bevin had been worried by the steadily hardening position of the Soviets towards Germany ever since the Potsdam Conference of July 1945 but had held out hope that a reconciliation was possible. However, relations between Eastern and Western Europe rapidly deteriorated after American Secretary of State George Marshall's offer of aid to Europe and the Soviet refusal to participate in the summer of 1947. Following Russian intransigence at the Council of Foreign Ministers in November and December 1947, Marshall feared that the USSR was shaping Eastern Germany into a totalitarian state akin to others in Eastern Europe, and he wrote that the ‘desire for an undivided Germany cannot be made an excuse for inaction in Western Germany, detrimental to [the] recovery of Western Europe as a whole’.

Consequently, on 23 February 1948, American and French delegations travelled to London at Bevin's invitation to begin a tripartite conference on the future of Western Germany. They were later joined by delegations from Holland, Belgium and Luxembourg, and, on 6 June 1948, released a joint communiqué announcing the merger of the three Western zones of Germany into a single economic unit with a single currency, the ‘West mark’, to begin circulating on 20 June. The Soviet authorities responded by stopping traffic on the autobahn into Berlin and delaying train services with lengthy inspections. On 21 June, they halted a US military supply train and prevented it from reaching Berlin. Finally, on 22 June, Marshal Vasily Sokolovsky, the head of the Soviet Military Administration in East Germany, announced that the Soviet Union would introduce with immediate effect an East German currency, which would become the only legal tender throughout Berlin, including in the Western zones. The United States and Great Britain responded by flooding Berlin with West marks printed with a special ‘B’ for Berlin, soon to become known as B-marks.