The unit traces its history back to 9 May 1917, the Aviation Section, U.S. Signal Corps, redesignated the unit as the 15th Aero Squadron on 22 Aug 1917. Flying historic aircraft like the Curtis "Jenny" JN-4 biplane, the squadron served as a flying training unit between 1917–1919. After a short stint on the inactive list and a series of organizational changes, the unit emerged as the 15th Observation Squadron on 25 Jan 1923. This began a varied and unending string of intelligence, surveillance, and reconnaissance roles for the unit that stretched over more than eight decades.