The Berlin blockade: Moscow draws the iron curtain

Berlin was carved into four zones at the end of World War II, each occupied by one of the Allied powers

The dust had barely settled on war-wracked Europe when, in 1946, Winston Churchill alluded to a new conflict that was set to engulf the continent - the Cold War.

"From Stettin on the Baltic to Trieste in the Adriatic, an iron curtain has descended across the continent," said Britain's war-time leader.

On April 1, 1948, the Soviet Union fired the first major salvo of that new conflict when it announced a crack-down on the free movement of traffic into Berlin.

A war of steely nerve

But instead of shelling and gunfire, the Berlin blockade and subsequent airlift was a war of steely nerve, logistics and diplomatic obstruction that left both sides wondering who would back down first.

Moscow's blockade of Berlin was calculated to oust the western powers who occupied the city with the USSR.

Germany was also split into four sectors, with Berlin in the heart of the Soviet zone

Berlin, like wider Germany, had been carved up into four sectors as part of the post-war peace deal worked out by the US, Soviet Union, Britain and France.

Each country controlled a sector. Berlin, Hitler's former powerbase and the focus of the Third Reich, had an anomalous position, located as it was deep in the heart of the Soviet-controlled part of Germany.

It amounted to a capitalist presence in the heart of a communist regime - a trophy for the western Allies but a mounting embarrassment to Moscow. While the Soviet Union was busy spreading its influence across eastern Europe, its former wartime allies were moulding their chunk of Germany into a free market, self-governing democracy.

Air access only

Their plans to launch a west German Deutschmark effectively scuppered any semblance of economic unity. The move infuriated Russia which resolved to force its former allies out of Berlin for good.

In truth the former capital had been under siege long before the start of the blockade in spring 1948. The only official access was along one of three 20-mile wide air corridors.

Stalin was determined to oust the western powers

Getting to Berlin by road or rail depended on the continuing co-operation of Soviet authorities. It meant west Berliners depended on Russian goodwill for deliveries of food, fuel and just about everything else.

East-West relations had deteriorated as each side vigorously pursued its own political course and on April 1 1948 Russia, under the leadership of Joseph Stalin, announced stringent controls on all overland traffic from western zones into Berlin.

At the mercy of the Soviets

Initially Moscow's tactics seemed to be based on little more than petty-minded bureaucracy. There were obstructions at crossing points, endless delays before trains could pass through signals, fussing over papers and roadblocks.

The uncomfortable reality, that the population of western Berlin were at the mercy of the Soviets, dawned rapidly.

British Prime Minister Clement Atlee showed a defiant side

Britain, under the leadership of Prime Minister Clement Atlee, and America, under Harry S. Truman, retaliated immediately with a small, but significant aerial supply campaign.

Stalin turned the screw, in May announcing restrictions that meant food parcels could no longer be sent into the Western zones.

Tension mounted throughout the spring and neither side was prepared to back down. Air traffic into the western zone was stepped up and on June 24 hostilities came to a head when the Soviets suspended all land travel into and out of Berlin.

It signalled the start of the most ambitious aerial supply campaign in history and, for almost a year, the city's inhabitants lived hand-to-mouth at the mercy of the Berlin Airlift.

• Blocked but not beaten, the airlift begins