This book recounts the development of aviation in the United States Army from April 1861, when the Army first became interested in balloons as a means of observation, to April 1917, when America entered World War I. The origins and organizations of the Army's air arm are told in detail, with particular emphasis on early air force personnel, planes, and experiments. In the process the monograph traces the early development of what today is The United States Air Force. Originally published by the United States Air Force in 1958.