Dear Mr. President, I hope you find this primer useful in answering your question of why there was a Civil War in the United States.
You see, once upon a time, some people decided that work would be a lot easier and cheaper if they didn’t have to do it themselves or hire others to do it for them, so they came up with the idea of buying human beings and forcing them to work for free in their fields. Naturally, people objected to being forced to work for free, so they beat some of them and killed others to set an example and “worker” complaints stopped.
They also decided that it would be pretty awesome to rape some of the women they bought. So they did.
And just to add the white supremacy cherry to being an insufferable asshole sundae, they also broke families apart and sold husbands, wives, and children to other insufferable assholes.
One day, some people said, “This is not cool and not Christian at all.”
The insufferable assholes said, “Totes cool, and look at these bible verses.”
The cool people said, “You’re kind of missing the point. We’re going to try to change the laws to stop this monstrosity.”
The insufferable assholes said, “We’re going to change the law to support it. And if you win control of the Presidency with this Lincoln character, we’re going to take up our ball and go home.”
The country elected Lincoln, and he was like, “Hey, guys, I’m cool.”
And the insufferable assholes of South Carolina said, “Fuck you, Abe” and shot at an American fort. Then they go together and drafted a letter of secession which said, “We love owning black people and you can’t make us stop, so fuck you, America.”
And then other states drafted letters of secession that said the same thing.
And the rest of America looked at their crazy ass backwater shitstain relatives and said, “You can’t leave the Union and you can’t own people and you shot up our fort. Of course you know, this means war.”
So we had a war and Robert E. Lee betrayed his country to go fight for the right to own people and was responsible for the deaths of more Americans than Al Qaeda could ever dream of killing.
But the cool people won the war, and slavery was outlawed. But the cool people weren’t exactly committed to the idea of letting black people be full citizens either, so rather than root out all of the insufferable assholes who killed good Americans, the ‘cool’ people just sort of forgot about everything and let the insufferable assholes continue to run the South and call slavery ‘share-cropping’ and ‘Jim Crow’. There was money to be made after all, and a few more Native American tribes to genocide.
And we all lived happily ever after… except for the native Americans and black people… and Chinese immigrants who built the railroads for us… the Irish for a while there, but they’re cool now… well, okay, the white folks lived happily ever after and that’s what really matters, right? (Just to be clear, Mr. President, this last paragraph was what we call sar-casm… have Ivanka look it up on Google for you, Sir.)