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.[1] Two days later, police and army engineers began to construct a more permanent concrete wall.[10] 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 mines, as well as channels of ploughed earth, to slow escapees and more easily reveal their footprints.[11]