In November 1961, Brig. Gen. Rollen Anthis (center) is pictured with his initial staff at Tan Son Nhut Air Base, Vietnam. By 1973, OSI District 50 at Tan Son Nhut was inactivated and eventually all OSI activity ceased except for the destruction of remaining records and evacuation of personnel which was known as Operation Blackbird. (U.S. Air Force photo)