The Harmon Memorial Lecture is the oldest and longest-running lecture series at the United States Air Force Academy, occurring continuously on an annual basis since the spring of 1959--before this institution had even graduated its first class. It is a fitting tribute to the man many consider to be the "father" of the Air Force Academy, its first superintendent, Lt Gen Hubert R. Harmon. General Harmon understood that the serious study of military history was an essential element of the military profession, and he was a strong supporter of the two main goals of the series: stimulating "cadets to develop a lifelong interest in the history of the military profession" and promoting the development and dissemination of military history for the benefit of all American citizens.Each year, the Academy's Department of History selects a leading military historian to present the Harmon Memorial Lecture to all cadets enrolled in the military history courses offered that term. For many years, these lectures were printed and disseminated individually across the Academy, the Air Force, and throughout academia. In 1988, Lt Col Harry Borowski, then a faculty member in the Department of History, edited a volume containing the first 30 years of Harmon Lectures. This volume picks up where Lieutenant Colonel Borowski left off, presenting the next 30 years of Harmon Lectures for the benefit of cadets, faculty and staff, the Air Force, scholars throughout academia, and all persons interested in military history throughout the world. Each of these volumes includes the work and wisdom of the finest military historians of their eras; the contributors represent a veritable Hall of Fame of military historians from 1959 to 2017General Harmon understood that military history served a special purpose for those in the American military profession--encouraging a warrior ethos, developing a deeper understanding of the profession of arms, and providing the context so absolutely essential for those entrusted with the security of the American Republic. I'm confident that readers from a wide variety of backgrounds will agree that this volume fully supports its intended purpose.