is chapter have been adapted from three historical papers [1] © 1982 IEEE, [2] © 1983 IEEE, [3] © 1983 IEEE with the permission of the Institute of Electrical and Electronic Engineers. The Historical Origins of Spread-Spectrum Communications has emerged from its cloak of secrecy. And yet the history of this robust mil- itary communication technique remains largely unknown to many modern communication engineers. Was it a spark of genius or the orderly evolution of a family of electronic communication systems that gave birth to the spread-spectrum technique? Was it, as Frank Lehan said, an idea whose time had come? Was the spread-spectrum technique practiced in World War II, as Eugene Fubini declares? Was it invented in the 1920s as the U.S. Patent Office records suggest? Was Theodore Sturgeon's lucid description of a jam- proof guidance system precognition, extrasensory perception, or a security leak? Let's examine the evidence, circa 1900-1960, concerning the develop- ment of spread-spectrum communications. 2.1 EMERGING CONCEPTS Before we can assess the ingenuity which went into the development of the first spread-spectrum systems, we must examine the development of com- munication theory and technology. When all the data has been reviewed, a case can be made for evolution and selection as the method by which progress has been made. A search for the origin of SS communications can become mired in the "definitionmanship" (a word coined by Robert Price in [3]) attendant to classification by order, genus, and species. The following will provide a database from which the reader may draw conclusions. 2.1.1 Radar Innovations From the 1920s through World War II, many systems incorporating some of the characteristics of spread-spectrum systems were studied. The birth of RADAR, i.e., RAdio Detection And Ranging, occurred in the mid-1920s when scientists used echo sounding to prove the existence of an ionized gas layer in the upper atmosphere. British scientists E. V. Appleton and M. F. Barnett performed this feat by trans