David Shoup (1904-1983) was a general in the United States Marine Corps, who served as the 22nd Commandant of the Marine Corps. As a colonel, he led the attack at the Battle of Tarawa, for which he received the Medal of Honor. He was appointed Commandant by Dwight D. Eisenhower.
Shoup advised against both the Bay of Pigs invasion and the commitment of U.S. ground forces in the Vietnam War. When the invasion of Cuba was first discussed, Shoup did a demonstration with maps. Placing a transparent map of Cuba over the United States, he surprised viewers that assumed it was a small island, not 800 mile long. He then put another transparent map overlay over Cuba, with a small red dot. Shoup explained that dot was the size of Tarawa, and "it took us three days and eighteen thousand Marines to take it." David Halberstam said Shoup became John F. Kennedy's favorite general, but Kennedy did not take Shoup's warning.
Shoup was more concerned with the Marine Corps than his role on the Joint Chiefs of Staff. In 1962, when Maxwell Taylor tried to expand the power of the Chairman of the Joint Chiefs of Staff, Shoup, along with GEN Curtis LeMay (Chief of Staff of the Air Force) and ADM David McDonald (Chief of Naval Operations), opposed Taylor. 
When intensified pressure against North Vietnam was being considered in 1963, Shoup did, however, support LeMay's proposal for a sharp and intense air campaign. . When he retired at the end of that year, the new Commandant, GEN Wallace Greene, intended to take a more activist role on the JCS. 
After his retirement, he did testify to Congress, in 1968, about his views on Vietnam. 
- Halberstam, David (1972), The Best and the Brightest, Random House, pp. 66-67
- McMaster, H. R. (1997), Dereliction of Duty: Johnson, Pike, the Joint Chiefs of Staff, and the Lies That Led to Vietnam, Harpercollins, p. 55
- McMaster, p. 59
- McMaster, p. 63
- "Present Situation in Vietnam. Hearing with General David M. Shoup, former Commandant, United States Marine Corps", Senate Foreign Relations Committee, March 20, 1968