Some context: Hattie McDaniel (June 10, 1895 - October 26, 1952) was an American stage actress, professional singer-songwriter, and comedian. She is best known for her role as "Mammy" in Gone with the Wind (1939), for which she won the Academy Award for Best Supporting Actress, the first Academy Award won by an African American entertainer. In addition to acting in many films, McDaniel was a radio performer and television star; she was the first black woman to sing on radio in the United States. She appeared in over 300 films, although she received screen credits for only 80 or so.
The whereabouts of McDaniel's Oscar are currently unknown. In 1992, Jet magazine reported that Howard University could not find it and alleged that it had disappeared during protests in the 1960s. In 1998, Howard University stated that it could find no written record of the Oscar having arrived at Howard. In 2007, an article in the Huffington Post repeated rumors that the Oscar had been cast into the Potomac River by angry civil rights protesters in the 1960s. The assertion reappeared in the Huffington Post under the same byline in 2009.  In 2010, Mo'Nique, the winner of the Academy Award for Best Supporting Actress, wearing a blue dress and gardenias in her hair, as McDaniel had at the ceremony in 1940, in her acceptance speech thanked McDaniel "for enduring all that she had to so that I would not have to". Her speech revived interest in the whereabouts of McDaniel's plaque. In 2011, J. Freedom duLac reported in the Washington Post that the plaque had disappeared in the 1960s.  In November 2011, W. B. Carter, of the George Washington University Law School, published the results of her year-and-a-half-long investigation into the Oscar's fate. Carter rejected claims that students had stolen the Oscar (and thrown it in the Potomac River) as wild speculation or fabrication that traded on long-perpetuated stereotypes of blacks. She questioned the sourcing of the Huffington Post stories. Instead, she argued that the Oscar was likely returned to Howard University's Channing Pollack Theater Collection between the spring of 1971 and the summer of 1973 or had possibly been boxed and stored in the drama department at that time. The reason for its removal, she argued, was not civil rights unrest but rather efforts to make room for a new generation of black performers. If neither the Oscar nor any paper trail of its ultimate destiny can be found at Howard today, she suggested, inadequate storage or record-keeping in a time of financial constraints and national turbulence may be blamed. She also suggested that a new generation of caretakers may have failed to realize the historic significance of the 5 1/2" x 6" plaque.
Why did the University have it?
A: 

Some context: Paul Warfield Tibbets Jr. was born in Quincy, Illinois, on 23 February 1915, the son of Paul Warfield Tibbets Sr. and his wife, Enola Gay Tibbets. When he was five years old the family moved to Davenport, Iowa, and then to Iowa's capital, Des Moines, where he was raised, and where his father became a confections wholesaler. When he was eight, his family moved to Hialeah, Florida, to escape from harsh midwestern winters. As a boy he was very interested in flying.
The 509th Composite Group returned to the United States on 6 November 1945, and was stationed at Roswell Army Airfield, New Mexico. Colonel William H. Blanchard replaced Tibbets as group commander on 22 January 1946, and also became the first commander of the 509th Bombardment Wing, the successor to the 509th Composite Group. Tibbets was a technical advisor to the 1946 Operation Crossroads nuclear tests at Bikini Atoll in the Pacific, but he and his Enola Gay crew were not chosen to drop another atomic bomb.  Tibbets then attended the Air Command and Staff School at Maxwell Air Force Base, Alabama. On graduating in 1947 he was posted to the Directorate of Requirements at Air Force Headquarters at the Pentagon. When the head of the directorate, Brigadier General Thomas S. Power, was posted to London as air attache, he was replaced by Brigadier General Carl Brandt. Brandt appointed Tibbets as director of Directorate of Requirements's Strategic Air Division, which was responsible for drawing up requirements for future bombers. Tibbets was convinced that the bombers of the future would be jet aircraft and thus became involved in the Boeing B-47 Stratojet program. He subsequently served as B-47 project officer at Boeing in Wichita from July 1950 until February 1952. He then became commander of the Proof Test Division at Eglin Air Force Base in Valparaiso, Florida, where flight testing of the B-47 was conducted.  Tibbets returned to Maxwell Air Force Base, where he attended the Air War College. After he graduated in June 1955, he became Director of War Plans at the Allied Air Forces in Central Europe Headquarters at Fontainebleau, France. He left Lucy and his sons behind in Alabama, and he and Lucy divorced that year. During his posting to France, he met a French divorcee named Andrea Quattrehomme, who became his second wife. He returned to the United States in February 1956 to command the 308th Bombardment Wing at Hunter Air Force Base, Georgia, and married her in the base chapel on 4 May 1956. They had a son, James Tibbets.  In January 1958, Tibbets became commander of the 6th Air Division at MacDill Air Force Base, Florida. and was promoted to brigadier general in 1959. This was followed by another tour of duty at the Pentagon as director of Management Analysis. In July 1962, he was assigned to the Joint Chiefs of Staff as deputy director for operations, and then, in June 1963, as deputy director for the National Military Command System. In 1964, Tibbets was named military attache in India. He spent 22 months there on this posting, which ended in June 1966. He retired from the United States Air Force (USAF) on 31 August 1966.
What rank was he when he retired ?
A:
In January 1958, Tibbets became commander of the 6th Air Division at MacDill Air Force Base, Florida. and was promoted to brigadier general in 1959.