The brain drain of professionals had become so damaging to the political credibility and economic viability of East Germany that the re-securing of the Soviet imperial frontier was imperative. Between 1949 and 1961, over 2½ million East Germans fled to the West. The numbers increased during the three years before the Berlin Wall was erected, with 144,000 in 1959, 199,000 in 1960 and 207,000 in the first seven months of 1961 alone. The East German economy suffered accordingly.On August 13, 1961, a barbed-wire barrier that would become the Berlin Wall separating East and West Berlin was erected by the East Germans. Two days later, police and army engineers began to construct a more permanent concrete wall. Along with the wall, the 830 mile zonal border became 3.5 miles wide on its East German side in some parts of Germany with a tall steel-mesh fence running along a "death strip" bordered by bands of ploughed earth, to slow and to reveal the prints of those trying to escape, and mined fields.
