 As there were no aviation engineering courses yet available he studied mechanical engineering at the Throop College of Technology (later Caltech) in 1910 and 1911, graduating with a B.S.Because of World War I, in 1916 Harold R. Harris joined a Citizen’s Military Training Camp at Monterey, California, which was one of the few with an aviation unit.Enrolling there he became an engineering officer in the First Provisional Aero Squadron.