At Delta-01, twenty feet underground, the Launch Center for Delta Flight's missiles operated behind the plain appearance of what looked like an average ranch house, even at the height of the Cold War. Personnel there worked as largely unseen and thankless "invisible warriors," including security police, facility managers, chefs, and others who remained on alert around the clock in an isolated setting. Security was kept at the highest level, and even Air Force personnel had to use the gate telephone to contact a security policeman inside and present the proper codes before being allowed entry.