There's an old, perhaps apocryphal story, about Ike, as a West Point cadet, writing a paper comparing and contrasting the leadership of Lee and Grant. When he started, he was going to go with the conventional belief that Lee was a genius that was overwhelmed by the numbers that Grant could throw at him, and that this was the only reason Grant was able to win. Reading the actual battle reports and records made him realize how wrong that assessment was.