"Since the beginning of time, man has sought protection from the dangers of a hostile environment. The cave, the forest, even hollow logs provided refuge for many of our forebears. Where the shelter and the actions taken were suitable to meet the emergency conditions, man survived. History contains countless references to individual, group, and community actions for protection from famine, flood, fire, and the effects of war. It was not, however, until the onset of World War II, with the threat of large-scale aerial attacks on cities and industrial centers, that civil defense planning gained impetus. Added impetus resulted from the advent of atomic and thermonuclear weapons and advanced delivery systems. […] The origin of civil defense preparedness in the United States may be traced to August 1916, when Congress established the Council of National Defense to coordinate 'industries and resources for the national security and welfare, and to create relations which will render possible, in time of need, the immediate concentration and utilization of the resources of the Nation'. The Council consisted of the Secretaries of War, Navy, Interior, Agriculture, Commerce, and Labor. In December 1918, this Council was dissolved, and from that time until 1940, civil defense in a formal sense did not exist in the United States. On May 28, 1940, President Roosevelt established the National Defense Advisory Commission, which included the Division of State and Local Cooperation. In May 1941, a Presidential Executive Order replaced the Division of State and Local Cooperation with the Office of Civilian Defense."
United States Emergency Management Institute: http://training.fema.gov/EMIWeb/edu/