There have been 74 four-star generals in the history of the United States Marine Corps. Of these, 56 achieved that rank while on active duty, 17 were promoted upon retirement in recognition of combat citations ("tombstone promotions", 1942–1959), and one was promoted posthumously. Generals entered the Marine Corps via several paths: 29 via Officer Candidates School (OCS), 25 via Naval Reserve Officer Training Corps (NROTC) at a civilian university, 10 via the United States Naval Academy (USNA), seven via ROTC at a senior military college, and three via Reserve Officers' Training Corps (ROTC) at a civilian university,
