The reason why you do history, and particularly why you do war, is that you want to make sure that in the next war, some lessons were learned. There's a saying: "History doesn't repeat itself, but it does rhyme." Or Ecclesiastes: "What has been will be again. What has been done will be done again." Human nature always superimposes itself - its strength and its frailty over the rush of chaos of ongoing events - and we can perceive patterns and themes and motifs.
I am passionately interested in understanding how my country works. And if you want to know about this thing called the United States of America you have to know about the Civil War.
World War II is smothered in sentimentality and nostalgia. What's interesting about Vietnam is that sentimentality is just not there, so you're given kind of a clean access to it in one way. It's also a war that represents a failure for the United States. Many people came back feeling like they never wanted to talk about it again. And so we developed a national amnesia.
I think we continually need to understand how important an event the war was - how defining, how central to who we are. Everything that came before it led up to it, and everything of importance to this country - at least up to 1940 - was a consequence of it. Even now there's an echo of the war, however faint, in almost everyone's life.