Throughout U.S. history, probably the same everywhere, incompetence has been more the rule rather than the exception.
That's the subject of Thomas Rick's recent book The Generals which is a compelling and riveting read.
During WWII, Sixteen Army division commanders were relieved for cause, out of a total of 155 officers who commanded Army divisions in combat during the war. At least five corps commanders also were relieved for cause.
The roster of losers is long; the list of heroes pretty short. Eisenhower was quite the exemplar, Matthew B. Ridgeway a battlefield hero, Leslie Groves a technocrat genius, maybe a handful of others.
IMNVHO, He was a true hero in his service to our country, but not so much on the battlefield