I read a very interesting account of how poorly Lee in particular and the Confederacy in general prosecuted the Civil War. They misunderstood their political goals absolutely and instead of simply fighting a war of defense - holding out long enough to appear a legitimate nation in their own right, (essentially running down the clock), they fought to take and hold territory that they didn't need. Tactical brilliance is nothing without sound strategy.

Montgomery vs Rommel is a good example of that too!

Politics again. Grant was a lousy president afterwards, and the south needed a hero. Thus their storylines diverge.

In fact, given the political needs in ensuing decades, there's really no need for the "story" to reflect the record at all.