The three western sectors of Berlin that were "floating" in the middle of the Soviet zone of Germany together with the policies of the western allies were a source of great irritation to the Soviets.
1st January 1947, the American & British zones of Germany combined to create the "Bizone" in order to stimulate a growing economy and encourage a new political order.
31st March 1948, the US Congress voted for 'Marshall Aid' which Stalin saw as an attempt to undermine Russian influence in eastern Europe. Immediately, the Soviets started stopping and searching all road, canal and rail traffic into Berlin.
23rd June 1948, the US & UK introduced a new currency into ‘Bizonia’ and western Berlin. People in eastern Europe began to change all their money into the new western currency, which they thought was worth more.
24th June 1948, the Soviets closed all canal, rail and land connections between the western sectors of Berlin and 'Bizonia'. The aim was to force the western powers to allow the Soviet zone to start supplying west Berlin with food and fuel, thereby giving the Soviets practical control over the entire city.
The road corridor was blocked and no trains or canal traffic was allowed through the Soviet sector of Germany into Berlin
The three air corridors were left unaffected as it was believed that it would be impossible for the western allies to transport the necessary supplies by air.
A further consideration was that to close the air corridors would require direct action, something that could quickly escalate into a major confrontation.
A cartoon of the time accurately describes the situation
However, resupply by air was exactly what the western allies decided to do using the three air corridors into Berlin.
Aircraft were loaded in the north at Fuhlsbüttel (with Finkenwerder & Lübeck) or in the south at Frankfurt (with Wiesbaden) .
Initially, Berlin had two airfields.......Tempelhof and Gatow but a third was built at Tegel (in the French sector) and was operational by November 1948.
The empty aircraft returned to their home airfield via the Celle corridor.
There are many excellent websites devoted to the history of the blockade (see Extras / Further Reading) but, in summary, over the next 318 days, over 275,000 flights delivered almost 2.5 million tons of supplies, just sufficient to maintain life in west Berlin.
Famous images which give a flavour of the airlift............the number of flights averaged 36 each and every hour for 318 days.
12th May 1949, seeing that the airlift was able to support Berlin, the Soviets lifted their blockade; supplies by rail, canal and road began once more.
The airlift continued at a reduced scale until the end of June 1949 when a three month surplus of supplies had been amassed.
It is interesting to note that the Berlin airlift could have been undertaken by just 17 C5 Galaxies.
The Galaxy has a load capacity of 270,000 pounds or over 122,000 kilograms.
The Douglas C-47 (the military version of the DC3 airliner) could carry around 7,500 pounds or 3,500 kilograms.
Seventy-eight people were killed during the operation, thirty-one American, thirty-nine British and eight German civilians.
Seventeen American and eight British aircraft crashed during the operation.
There are three identical airlift memorials in Germany........at Tempelhof in Berlin and the airports in Celle & Frankfurt am Main.
The curved concrete structures – designed by Eduard Ludwig – have three claws facing westwards to symbolise the three air corridors and the three Allied occupying forces.
The original memorial in Tempelhof was dedicated in 1951 and the replicas in Frankfurt am Main and Celle were unveiled in 1985 and 1988. No memorials are in place for the northern corridor.
The three memorials (L to R)...........Tempelhof (Berlin), Frankfurt and Celle.
Click the image or this link for a larger version.