Some people seem not to have noticed that the civil war was fought over "union" and whether citizens were citizens of the federal government as well as the states, as well as the slavery question. So they are fantasizing.
I'd prefer it not to take a quarter of the population to settle the question.
UPDATE: Decimal point error. That's two point five percent, not twenty five percent. Still not good: today's population would make that over seven and a half million.