(Reuters) - A red torch flickered in the shadows of the Brandenburg Gate as I drove down a deserted Unter den Linden toward the main crossing point between East and West Berlin in the early hours of August 13, 1961.
It was a border policeman waving me down. He strolled casually over and declared: "I'm afraid you cannot go any further. The border is closed (Die Grenze ist geschlossen)."
These were momentous words in Europe's post-war history. I did not stay to argue but turned the car around and headed back toward the office-flat which Reuters rented in the Schoenhauser Allee (in East Berlin) about a mile away.
At the edge of the huge Karl Marx Platz, the square where the Communist regime held all its ceremonial parades, a soldier with another red torch stepped out and stopped my car.
Before I had time to protest, a long column of trucks filled with police and factory fighting guards, as the East German militia were then known, streamed for some 10 minutes across the square and disappeared at speed into the darkness toward the Brandenburg Gate.
I returned to the office, "white to the lips" as my wife's diary of the time records, and sat down at the teleprinter to file a message to headquarters in London - "The East-West Berlin border was closed early today."
It was a world scoop by eight minutes.
As it happened, one of the largest police stations in East Berlin was a few doors away from the Reuters office. Within a few minutes, the tranquility of the warm summer night was broken by the roar of trucks and motorcycles as it was turned into an operational headquarters for the border-closing operation.
But in most of East Berlin the population slept still unaware of what was happening. All night the radio broadcast a series of decrees, interspersed with jazz records. As people woke up, they could hardly believe what they heard.
Everybody had been expecting the Communist regime of Walter Ulbricht to take drastic measures to reduce the flow of East Germans crossing to the West. But a wall through the entire city? Impossible!
Now it was happening. No one knew for how long, and many believed in those first hours the restrictions would last only a few weeks or months.
But a dawn drive to the Brandenburg Gate suggested something else. Trucks were unloading concrete slabs and militiamen were uncoiling rolls of barbed wire. At the hundreds of other crossing points, the wall was still a solid line of grim-faced militiamen.
As the morning wore on, crowds began to build up on both sides. East Berlin police and factory guards patiently pushed the sullen but mostly orderly crowds back, yard by yard, hour by hour, until by mid-afternoon the border was out of sight. Then, in Schoenhauser Allee at least, they quickly dispersed the crowds with tear-gas volleys.
Fellow Reuters correspondent Peter Johnson landed at East Berlin's Schoenefeld airport that afternoon from an assignment in Moscow and found the airport encircled by troops.
Our account of the Wall story was read throughout the world. A few months later a senior East German ambassador in a neighboring Communist country, congratulated me on Reuters coverage. "It was the only means we had of really knowing what was happening in our country," he told me.
How did I happen to be at the Brandenburg Gate in the early hours of August 13?
An anonymous phone call after midnight from a man speaking in German implored: "I strongly advise you not to go to bed tonight."
Later the East German news agency ADN's teleprinter clattered into life with a communique from Moscow urging "effective control" around West Berlin.
That was the signal. I rushed out into the night and a date with history.
Filed by Jeremy Gaunt