And that, perhaps, is where the contrast between Grant and Lee becomes most striking. The Virginia aristocrat, inevitably, saw himself in relation to his own region. He lived in a static society which could endure almost anything except change. Instinctively, his first loyalty would go to the locality in which that society existed. He would fight to the limit of endurance to defend it, because in defending it he was defending everything that gave his own life its deepest meaning.
The Westerner, on the other hand, would fight with an equal tenacity for the broader concept of society. He fought so because everything he lived by was tied to growth, expansion, and a constantly widening horizon. What he lived by would survive or fall with the nation itself. He could not possibly stand by unmoved in the face of an attempt to destroy the Union. He would combat it with everything he had, because he could only see it as an effort to cut the ground out from under his feet.
Read the rest of Bruce Catton's "Grant and Lee: A Study in Contrasts."