By 1961, Berlin was the gap in East Germany’s border controls that the government could not close by ordinary travel restrictions. Although the inner German border had been shut in 1952, Berlin remained divided among the four occupying powers, and its sector boundary was still accessible. East Germans could cross from East Berlin into West Berlin and continue to West Germany or other Western European countries.
The scale of this departure drove the decision to build the Wall. Before it was erected, 3.5 million East Germans, about 20 percent of the population, had left the GDR; many were young, educated professionals. East German leaders feared the resulting loss of engineers, doctors, teachers, and skilled workers, while the contrast with West Berlin made it harder to defend the communist system.
On 13 August 1961, East German police and army units sealed the border with West Berlin, tore up streets, and put up barbed wire and fences. The barrier was built on East German territory and later developed into a guarded concrete system around West Berlin. Its final form included watchtowers, signal fences, trenches, dogs, and a cleared area between barriers known as the death strip, where guards had a clear view and line of fire.
The GDR called the Wall an Anti-Fascist Protection Rampart and said it protected the population from hostile Western forces. West Berlin Mayor Willy Brandt called it the “Wall of Shame,” referring to its restriction of movement. In practice, the Wall largely stopped the emigration that had weakened East Germany.
The Wall opened when pressure for change spread through the Eastern Bloc in 1989. After weeks of civil unrest, the East German government announced on 9 November that GDR citizens could visit West Germany and West Berlin. People crossed and climbed the Wall that night; the Brandenburg Gate section reopened in December, demolition began in June 1990, and German reunification formally followed on 3 October 1990.