During the night of 12 to 13 August 1961 the National People's Army, the German Border Police, the Volkspolizei and the Combat Groups of the Working Class locked down all passages between the Soviet sector and the three West sectors; construction of border protection facilities began.
Pada malam 12 sampai 13 Agustus 1961, Tentara Rakyat Nasional, Kepolisian Perbatasan Jerman, Volkspolizei dan Kelompok Penyerang Kelas Buruh menutup semua perlintasan antara sektor Soviet dan tiga sektor Barat; pembangunan fasilitas perlindungan perbatasan pun dimulai.