Major Walter Reed, M.D., September 13, 1851 – November 23, 1902, was a U. S. Army physician who in 1900 led the team which postulated and confirmed the theory that yellow fever is transmitted by mosquitoes, rather than by direct contact. This insight gave impetus to the new fields of epidemiology and biomedicine, and most immediately allowed the resumption and completion of work on the Panama Canal, 1904–1914 by the United States.