The decision to create this subterranean command center arose from the stark realization that modern warfare had fundamentally changed the nature of conflict. The devastating air raids of the Spanish Civil War and the early campaigns of World War II had demonstrated that no location, however prestigious or well-defended on the surface, could be considered safe from aerial bombardment. The traditional seats of power, with their grand windows and impressive facades, had become death traps in an age of strategic bombing.
Construction of what would officially be known as the Central War Room began in earnest during the summer of 1938, as the Munich Crisis made clear that European war was not a matter of if, but when. The Office of Works, under the direction of Sir Raymond Unwin, faced the monumental task of creating a bombproof facility capable of housing the highest levels of government while maintaining absolute secrecy about its location and capabilities.