Operations research (OR) emerged during World War II as an important means of assisting civilian and military leaders in making scienti?cally sound improvements in the design and performance of weapons and equipment. OR techniques were soon extended to address questions of tactics and strategy during the war and, after the war, to matters of high-level political and economic policy. Until now, the story of why and how the U.S. Army used OR has remained relatively obscure, surviving only in a few scattered o?cial documents, in the memories of those who participated, and in a number of notes and articles that have been published about selected topics on military operations research. However, none of those materials amounts to a comprehensive, coherent history. In this, the ? rst of three planned volumes, Dr. Charles R. Shrader has for the ?rst time drawn together the scattered threads and woven them into a well-focused historical narrative that describes the evolution of OR in the U.S. Army, from its origins in World War II to the early 1960s. He has done an admirable job of ferreting out the surviving evidence, shaping it into an understandable narrative, and placing it within the context of the overall development of American military institutions. Often working with only sparse and incomplete materials, he has managed to provide a comprehensive history of OR in the U.S. Army that o?ers important insights into the natural tension between military leaders and civilian scientists, the establishment and growth of Army OR organizations, the use (and abuse) of OR techniques, and, of course, the many important contributions that OR managers and analysts have made to the growth and improvement of the Army since 1942. In this volume, Dr. Shrader carries the story up to 1962, the beginning of the McNamara era and of America’s long involvement in Vietnam. The subsequent volumes will cover Army OR during the McNamara era; its application in support of military operations in Vietnam; and its significant contributions to the Army’s post–Vietnam recovery and reorganization, ultimately leading to a victory (after only 100 hours of combat) in the first Gulf War in 1991 and the emergence of the U.S. Army as second to none in modern weaponry, tactical prowess, and strategic vision.