This volume describes and evaluates the record of the Chemical Warfare Service in developing, procuring, and issuing munitions of chemical warfare to the Army and Navy from the inception of the service in world War I. In that war, with the assistance of the Bureau of Mines and the National Research Council, the service developed toxic agents and protective equipment and procured them on a large scale, though few of the items produced had reached the troops of the American Expeditionary Forces when the war ended (Chapter I). In the postwar years of military economy the service could keep only a nucleus of scientists at work on the discovery and designing of its munitions (Chapter II). In the field of procurement and distribution its activity, except for planning, was limited almost entirely to gas masks, manufactured at Edgewood Arsenal and stored at the Edgewood depot (Chapter X).Increased appropriations and rapid expansion came with the semimobilization of 1939-41, when the service built new laboratories, plants, arsenals, proving grounds, and depots, and began to stock chemical munitions (Chapter X), while its scientists watched the development of munitions that were proving useful in Europe (Chapter II).The service expanded very rapidly after the United States entered the war. At the heart of its special activities was an augmented technical staff, which worked with the assistance of the Office of Scientific Research and Development and other civilian agencies. The mission of the service was extended to include the offensive and defensive aspects of biological warfare, long under discussion, and now recognized as a serious threat (Chapter V). In pursuing its original mission the service searched for more effective war gases (Chapter III), and better means of physical protection against toxic agents (Chapter IV). It also improved the 4.2-inch chemical mortar into an extremely effective high explosive as well as chemical weapon (Chapter VI); developed what were essentially new weapons: flamethrowers (Chapter VII) and incendiaries (Chapter VIII); and provided better screening smokes and smoke generators (Chapter IX).The service manufactured these munitions in its arsenals and plants and also procured great quantities of them through contracts with private industry. In addition to problems of procurement that it shared with the other technical services, the Chemical Warfare Service had its own, such as those incident to the relatively modest size of its contracts, and the fact that most of its items had not reached an advanced stage of development (Chapters XIII-XV). The service also had peculiar problems of storage and distribution (Chapter XVI) and unusual difficulties in the field of property disposal (Chapter XVII) because of the nature of its munitions.