What lesson did you learn from the civil war?

That my ancestors should have simply "let go" and allowed the south to secede and work out their own destiny. We could have avoided 600,000 deaths from combat casualties and battlefield diseases. Slavery would've been resolved in the Confederate States within 25 years anyhow. There would've been no reconstruction period disasters. And the south could now be putting whatever science medieval fairy-tales and history revisions that they want in their high school text books and it wouldn't cause us in the north any sleepless nights. [But, of course, they wouldn't be because then they'd shrivel up into more of an economic irrelevancy than they already were next to their northern brothers.] Texas could execute anyone and everyone they want...and Rick Perry would probably be viewed as a southern progressive instead of the barbarian Hun with good hair that he actually is.