Emphasizing research and development, stepped-up aircraft production, crew training, and the growth of air bases, General Henry Harley Hap Arnold also advanced the doctrine of long-range strikes rather than support of ground forces as the air arm’s primary combat strategy. Dik Alan Daso describes the technology, institutions, and individuals that influenced Arnold’s decisions and shows how the peacetime experiences of World War II’s foremost military airman shaped the evolution of American military aviation.