Pershing was made a six-star general, so that he would be equal in rank to British and French field-marshals, the only six-star in U.S. history. Eisenhower only needed five stars, since I suppose that the U.S. felt that since it was supplying the bulk of the men and material in Western Europe, we didn’t need shoulder boards to assuage national pride.
I recall at the time of Washington’s posthumous promotion, that the purpose was to insure that Washington would be equal in rank and superior in date of rank to Pershing.
We stopped making five-star (General of the Armies) after World War II.
I did not know that. I thought he was just five star.