In 1783, when the first practical aircraft (hot-air and hydrogen balloons) were established, they were quickly adopted for military duties.^[2] The first military balloon unit was the French Aerostatic Corps, who in 1794 flew an observation balloon during the Battle of Fleurus, the first major battle to feature aerial observation.^[3] Balloons continued to be used throughout the 19th Century, including in the Napoleonic Wars and the Franco-Prussian war, for observation and propaganda distribution.^[4] During the First World War, German Zeppelin airships carried out multiple air raids on British cities, as well as being used for observation.^[4] In the 1920s, the U.S. Navy acquired several non-rigid airships, the first one to see service being the K-1 in 1931. Use by the US as well as other countries continued into the Second World War, the US Navy finally retiring its last balloons in 1962.^[5]

Heavier-than-air[edit]

Soon after the first flight of the Wright Flyer, several militaries became interested in powered aircraft. In 1909 the US Army purchased the Wright Military Flyer, a two-seat observation aircraft, for the Aeronautical Division, U.S. Signal Corps. It served until 1911, by which time powered aircraft had become an important feature in several armies around the world.^[6] Airplanes performed reconnaissance and tactical bombing missions in the Italo-Turkish war, and the First Balkan War saw the first naval-air operations. Photoreconnaissance and propaganda leaflet drops followed in the Second Balkan War