The East German regime obviously expected trouble forty years ago, when it decided to build a wall to divide Berlin.

The Stasi, East Germany's infamous secret police, devoted nearly all their resources and 50 000 staff to the job for a whole year. And timed the operation to begin shortly after midnight, on a Sunday.

More than 75 000 people were imprisoned for trying to escape. On average, one every three and a half hours every day for 28 years.

These figures are the result of the latest research, drawn up by two historians who work at the BstU, the institute which holds the files of East Germany's secret police, published recently. More than 800 people were killed trying to escape - an approximate figure, even now. They died trying to escape over the wall, at the borders, or drowned in the Baltic Sea.

On the Brink of War

These people attempted to escape from East Germany because they were suddenly locked in. Until the late 1950's, underground trains still connected the Soviet sector with the other allied zones. The loophole had to be plugged, according to the intellectual architect of the wall, Walther Ulbricht, Chairman of the SED, the socialist dictatorship that ruled East Germany. In order to avoid the Soviet Sector being drained, those inside the sector had to be prevented from leaving. 2.7 million had already done so by August 13, 1961.

At 3.25 on the morning of the 13th, RIAS, "Radio in the American Sector", reported that the entire border around West Berlin had been closed. The operation had taken little more than three hours. Overnight, the population of an entire city had been taken by surprise.

Once again, the world stood on the brink of war and nuclear capabilities overshadowed the possibility of a limited theatre.

The Soviets had successfully completed testing an intercontinental ballistic missile. And in October 1961, US tanks stood face-to-face with Soviet tanks at Checkpoint Charlie in Berlin. Politically it was perhaps one of the most volatile moments in modern history. Thanks to the efforts of a middle man, however, who mediated in the crisis, the tanks withdrew.

It was to take 28 years until the wall was torn down again.

So many unanswered questions

How the decision was taken to close the borders to the West and who knew about it, remains nebulous at best. Many questions still remain unanswered: Did Khrushchev order the closure or did he make a secret deal with Kennedy? How long in advance did Western intelligence services know about this, and why did the allied powers do nothing to stop it? Why didn't they warn the people in the Soviet sector that it was about to happen?

So far, miles and miles of secret police files have still not provided the answers, twelve years after the wall came down and forty years after the wall was built.