The 85th Aero Squadron was an Air Service, United States Army unit that fought on the Western Front during World War I. Initially assigned as an Army Observation Squadron to perform long-range strategic reconnaissance behind enemy lines, it was instead designated as a Corps Observation Squadron, performing short-range, tactical reconnaissance over the VI Corps, United States Second Army sector of the Western Front in France. There is no modern United States Air Force unit that shares its lineage and history.