Check yer history sport....Eisenhower then a four star (at that point the highest rank in the US military) commanded Montgomery a British Field Marshal. Montgomery and the British public (with Montgomery's urging) thought the insufferable prick had been "demoted" when Bradley arrived and took over command of American forces shortly after D-Day. (per the plan all along)
The five star rank was used during WWII only and when the holders of that rank retired or died....the rank went with them. Four stars are the limit today.