Only five U.S. Army General Officers have ever held the five-star rank, which was established in December 1944 and titled General of the Army—a somewhat unfortunate titular choice given that three Army Generals (Grant, Sherman, and Sheridan) had previously been named General of the Army but wore fewer stars. (Even more confusing is that the two officers named to the higher-ranking position General of the Armies, George Washington and John J. Pershing, never even wore five stars.)
The five five-star Army officers were Generals George C. Marshall, Dwight D. Eisenhower, Douglas MacArthur, Henry H. Arnold, and Omar N. Bradley. Of these, Henry Arnold went on to be named to a five-star rank in another branch of the United States Armed Forces—General of the Air Force—in 1949, a position that was never filled after his death just eight months after he was so honored. Following the death of Omar Bradley in April, 1981, the five-star Army rank was eliminated.
This insignia was worn on the epaulets of the Class A Army Green uniform and the jacket of the Air Force Service Dress uniform. A dedicated Internet search will reveal images of both Bradley and Arnold wearing the insignia on the epaulets of their respective uniforms, positioned near the squared end of the epaulet (beside the shoulder seam).
The five-star rank was also established in the Navy at the same time as in the Army, and the Navy's first three Fleet Admirals—William Leahy, Ernest King, and Chester Nimitz—were named between 15 December and 19 December 1944. Nearly a year would elapse before William "Bull" Halsey would take the oath to become the service's fourth and final Fleet Admiral. Although the Navy has not had a Fleet Admiral since the passing of Chester Nimitz in 1966, the rank is still in the Navy command structure and could be filled at the discretion of the United States Congress. Should that happen, the nonsubdued pin-on Fleet Admiral insignia would be authorized for wear on the blue jackets and all-weather coats, black jackets, and khaki jackets in accordance with NAVPERS 15665I.