Fully illustrated with color photographs. EP 870-1-70. Traces the federal program from its tentative beginnings in the 19th century to the enactment of a permanent federal policy on disaster assistance in 1950. Explains how the Engineers came to acquire that mission during the great Mississippi River flood of 1882. Describes the development of the Corps' statutory authorities and the Army's regulations for emergency operations. Tells the stories of Corps and Army Engineer operations during various calamities.