Greer returned to the United States in September 1945, in a
record-setting long-distance flight from Hokkaido to Chicago. His first post-war assignment was at
Wright Field, Ohio, as assistant to the chief of administration for technical matters of the
Air Materiel Command from 1 February to 29 August 1946. He was then selected as an instructor in
electrical engineering at West Point. As a preliminary, he attended
Columbia University from 26 September 1946 to 26 May 1947. He then taught at West Point until 22 July 1949. He transferred to the newly formed
United States Air Force (USAF) on 1 July 1948, and on 23 July 1949 he was assigned to USAF Headquarters at
The Pentagon in Washington, DC, where he worked in the Office of the Assistant for Atomic Energy. He was promoted to
colonel on 22 June 1950. He attended the
Air War College, remaining as an instructor after graduation in 1953. He was posted to
Supreme Headquarters Allied Powers Europe (SHAPE) in
Paris in July 1954, to serve on the staff of British
Field Marshal Lord Montgomery. Afterwards he joined the staff of the
49th Air Division in the UK, and then the
Third Air Force there as its director of operations and deputy chief of staff for operations. In July 1957, Greer returned to USAF Headquarters as the deputy assistant chief of staff and then, in July 1959, assistant chief of staff for guided missiles with the rank of
brigadier general. He then became the
Air Force Ballistic Missile Division's vice commander for satellite systems. In the wake of a reorganization of the
Air Research and Development Command and the
Air Materiel Command on 1 April 1961, he became the vice commander of the
Air Force Systems Command's
Space Systems Division (SSD), which was based at
Inglewood and later
El Segundo, California. He was promoted to
major general in July 1961. As vice commander of SSD, was also head of the
SAMOS Program Office. As such, he reported directly to the
Under Secretary of the Air Force,
Joseph V. Charyk. He was also the West Coast director in the USAF Office of Missile and Satellite Systems. In July 1961, the SAMOS Project Office became the USAF element of the
National Reconnaissance Office (NRO). The USAF element became Program A on 23 July 1962, and embraced both the NRO
Defense Meteorological Satellite Program and the secret
reconnaissance satellite programs. Greer retired on 1 July 1965, but elected to remain in southern California. He became president of a division of
Rockwell International. He died from
pancreatic cancer in
Escondido, California on 11 February 1976, and was buried in Westminster Memorial Park in
Westminster, California. ==Dates of rank==