26 May 1952, the generally unfortified nature of the border between East and West Germany ended when East Germany implemented a "special regime on the demarcation line".
By 1952 the GDR had already blocked many unofficial crossing points with ditches and barricades but the new measures were on a completely different scale.
The fortification of the border resulted in the severing of 32 railway lines, 3 autobahns, 31 main roads, 8 primary roads, about 60 secondary roads and 1000s of lanes and tracks.
The images show the strip being ploughed in rural areas and fencing erected through urban stretches
All this was justified as a measure to keep out 'spies, diversionists, terrorists and smugglers' but in reality it was to prevent the many skilled, educated and professional classes from leaving. The continuing loss of 10-20,000 such citizens per month threatened the viability of East Germany's economy.
The border between East & West Germany was known as the Inner German Border and stretched 1,393 kilometres from the Baltic Sea to Czechoslovakia
It is interesting to note that the border system of Czechoslovakia was not as elaborate and fortified as the Inner German border but it was considered difficult to cross the border undetected.
On the 15th December 1952 freedom of travel for individuals within the GDR was limited to 100km unless special permision was granted.