On 13 August 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 (1336 km) zonal border became 3.5 miles (5.6 km) wide on its East German side in some parts of Germany with a tall steel-mesh fence running along a "death strip" bordered by mines, as well as channels of ploughed earth, to slow escapees and more easily reveal their footprints.
