Predating World War II, John J. Pershing held the rank of "General of the Armies." He never wore the 5-star rank.
In December 1944 the following received 5 star rank:
Fleet Admiral William Leahy dor - 15 December 1944
General of the Army George Marshall dor - 16 December 1944
Fleet Admiral Ernest King dor - 17 December 1944
General of the Army Douglas MacArthur dor - 18 December 1944
Fleet Admiral Chester Nimitz - dor - 19 December 1944
General of the Army Dwight Eisenhower dor 20 December 1944
General of the Army Henry Arnold dor 21 December 1944
Fleet Admiral William Halsey promoted in December 1945
In 1949 after the Air Force was created as a separate service, Arnold's rank was changed to General of the Air Force.
In September 1950, Omar Bradley, General of the Army became the 9th officer to achieve 5-star rank, one day after Marshall became Secretary of Defense.
In 1976 President Gerald Ford promoted George Washington to the same rank as that which had been held by Pershing-- General of the Armies, specifying that Washington would rank first among all generals past and present. Washington is not considered to have held 5-star rank.
So only 9 men have held 5-star rank; Five of them from the Army, 4 from the Navy and 1 from the Air Force.
Source: Five Star Rank by Roger D. Cunningham. MC&H Vol. 54, No. 3, p. 129.
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