East Germany used the code name Operation Rose for the secret 1961 operation that built the Berlin Wall.
The operation began shortly after midnight on 13 August 1961. East German police, border guards, and military units sealed roads and rail links between East and West Berlin. Barbed wire appeared first, followed by more permanent barriers. The operation’s secrecy was intended to prevent a mass flight of East German residents and to limit the possibility of organized resistance.
The name is sometimes confused with a general description of the Berlin Wall’s construction, but Operation Rose specifically refers to the initial state operation that closed the border. The first barriers were relatively improvised; later versions became a heavily engineered border system with concrete segments, patrol roads, fences, lighting, and a restricted strip. The operation transformed Berlin’s political division into a physical one almost overnight.