Like its collapse 28 years later, the construction of the Berlin Wall in 1961 was precipitated by a flood of refugees from east to west but that exodus was triggered by a succession of bungled diplomatic manoeuvres. At the end of the second World War in 1945, the four victorious allied powers – the United States, the Soviet Union, Britain and France – had put Germany under joint occupation, with each administering a zone of the country. Berlin, which was 176km inside the Soviet zone, was also under joint allied authority, with each of the four powers governing a sector.

After the establishment of the Federal Republic of Germany in the west and the communist German Democratic Republic in the east, Berlin was an anomaly and the Soviets were eager to incorporate the city into their German satellite state. They tried to drive the western allies from Berlin in 1948 by blocking access from West Germany by road and rail but the allies kept the western sectors of the city supplied with food and other necessities through an airlift lasting more than a year.

Diplomatic offensive

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By the late 1950s, Soviet leader Nikita Krushchev had launched a diplomatic offensive aimed at international recognition of the East German communist state and the transformation of Berlin into a demilitarised “free” city. At a summit in Vienna on June 4th, 1961, Krushchev issued an ultimatum to president John F Kennedy, threatening to unilaterally dissolve the four-power agreement over Berlin and to hand over to East Germany control of transit routes to the city from the west unless there was a deal within six months.

Kennedy made clear his commitment to defending the western sectors of the city but not the special status of Berlin as a whole, a message he and senior US officials reinforced in the weeks after.

Fears that the border would be sealed had prompted growing numbers of East Germans to cross into the west during the early months of 1961 and the flow of migrants, many of them highly skilled, now turned into a torrent, with more than 1,000 a day arriving at a reception centre in Marienfelde. East German leader Walter Ulbricht had long been pressing Kruschchev to allow him to stem the flow of refugees by sealing off West Berlin and had been stockpiling building materials and barbed wire.

Barbed wire

At midnight on Saturday, August 12th, 1961, East German police started erecting barbed wire around the 156km circumference of West Berlin and, by morning, the western sectors of the city were sealed off. The Soviets had suggested the use of barbed wire so that the barriers could be removed quickly if there was an aggressive response from western allied forces. Once it was clear the US and its allies were willing to accept the partition of Berlin, the barbed-wire barrier was reinforced with a second, parallel fence and finally replaced by a concrete wall, 3.6m high. Over the years, the wall was strengthened so that by the time it was removed in 1989, it was fortified with death strips, anti-vehicle trenches and dog runs, and overseen by 116 watchtowers.