 The Army also used balloons during the Spanish–American War and World War I, but airplanes replaced balloons for most military purposes during the latter conflict.While not part of the present Army Aviation Branch's heritage, United States military aviation began in 1907 with the Signal Corps Aeronautical Division and its acquisition of its first heavier-than-air aircraft, an airplane built to Army specifications by the Wright brothers.During World War I, the Air Service's aircraft strength grew from a few dozen to more than 11,000 planes, and the number of aviation personnel came to total more than 190,000.