In 1976, former US President Richard Nixon, having toured one of the tunnel shelters near Tiananmen constructed as part of the 1969 mass campaign remarked: ‘“having a shelter makes it less likely you will have to use it.’” Based on previously untapped archival documents from the American, British, Chinese, Dutch, French and German archives, this paper looks at the 1969 mass shelter construction campaign as both a performance for a foreign audience and a domestic attempt to exert control by militarising space. In the scarce English-language scholarship on Chinese civil defence, there is a tendency to frame Chinese responses to the nuclear threat through the lens of diplomatic or social history, largely disregarding the militarisation of space as a tool of domestic governance. This paper argues that judging from the resulting infrastructure, the 1969 mass shelter campaign was as concerned about a potential nuclear war as it was about mobilising and disciplining the masses. By recalling memories of World War Two and highlighting contemporary threats against China, the Party sought to justify “voluntary” shelter digging to a country torn apart by the Cultural Revolution. While mass mobilisation was to an extent successful in mobilising the people for their own wartime defence, digging was also a “political task” that put people under pressure to deliver, at times resulting in implementation shortcomings ranging from water damage to blossoming underground populations of mosquitos and toads.