Oliver Niess was commissioned through the Reserve Officer Training Corps program in 1925 upon graduation from Washington University, St. Louis, Missouri, and continued his studies to receive his doctor of medicine degree in 1927. After serving as a Medical Officer in the Army Air Forces in World War II, he transferred to the U.S. Air Force when it became a separate branch of service in 1947. From 1958 to 1963 he served as the 4th Surgeon General of the Air Force. He retired in 1963 as a U.S. Air Force Major General.