Rising to the rank of Generalleutnant (Lieutenant General), he was an official observer with the Union Army during the American Civil War, where he studied the use of balloons. This aroused his interest in aeronautics and after retiring from the army in 1891 he devoted his attention to the design and construction of airships. The maiden flight of his first airship took place in 1900 and later successes established the feasibility of passenger and goods transportation by air.