We all know that the Civil War happened because of slavery. The South fought for the right to keep African-Americans as slaves, the North fought to outlaw slavery. While this is a bit of an oversimplification, it isn't wrong.
Here's the funny thing: Only 25% of white Southerners held people in slavery (I chose not to use the term "owned," because we shouldn't be allowed to own other human beings). Only 12% of those slaveholders held more than 10 people in slavery.
In other words, slavery was only economically dominant for about 3% of white Southerners. And yet, the South went to war, and over 260,000 Confederate soldiers died (out of a white population of 5.5 million).
In other words, nearly 5% of the white Southern population died in a war which was fought for the economic interests of about 3%. The equivalent death toll for today's US population would be over 15 million, or greater than the population of any state other than California, Texas, Florida, or New York.
The antebellum South had a level of wealth inequality that would shock Piketty. And yet, the 97% went willingly to fight in a ruinous war that offered them little economic benefit.
One explanation that strikes me as both sad and terribly plausible is that focusing on keeping slaves in an inferior position in society allowed poor white Southerners to feel better about their own situation. Rather than highlighting the gap between rich and poor, Southerners chose to cast the spotlight on the gap between free and enslaved.
Today, more than 150 years after the end of that terrible war, and the even more terrible institution of slavery, we still have politicians trying to divide us, and offering to make some groups feel better by demonizing and denigrating others. Hopefully those who follow these kinds of politicians stop to ponder the fate of the antebellum Southerners who allowed their prejudices to carry them into disaster.
UPDATE: The statistics cited above come from "The American Civil War," from The Great Courses. The professor for the course is Gary Gallagher of the University of Virginia.