Martin Q. Blank said:
The 13th amendment barely passed the House without the southern states. If they were still in the union, it would never have been close. Much less ratification. Just stay in the U.S. and vote against it.
If, by some means, they do ban slavery, then secede. Doing it early took away their voting power.
Also, if the position of the U.S. was that secession was illegal, why weren't the southern states given a vote in the 13th amendment?
Slavery was an important issue but it wasn't THE issue, abolition certainly wasn't the reason with Delaware, Maryland, Kentucky, and Missouri also slave states and New Jersey only banning slavery a few years before. Lincoln also made it clear he was willing to do anything the South wanted to make slavery safe it prevented them from seceding.
The South left because it was tired of fighting with the North and having to cede so much power to people in New York and Boston and so on that they had less and less in common with. They wanted to have their own self determination and be independent. The South never saw the US the same way as we do now, they saw it far more of an alliance of states and most Southerners saw their state as their country. They wanted to leave.
Was slavery an important part of that? Sure, the entire economy of the South was reliant on it not only for farming but it was a huge asset for most families of wealth. Ironically the banning of importing new slaves drove the price of slaves up significantly.which made it harder for them to give them up. With most plantation owners being rich in land but capital poor that would have bankrupted much of the South and make no mistake the banks in the North were also positioned to come in and repossess as much of that property as possible which is essentially what the Carpetbaggers ended up doing after the War. They had good reason to be paranoid. It's also very difficult for anyone today to understand the complexities of slavery in that time in both the North and South yet most people think that everyone in the North were abolitionists while everyone in the South was a slave owning racist dreamed about whipping them at night. The truth is very different, there were some terrible and wonderful people on both sides. For 100 years after the Civil War people understood that and found peace with it but that's long gone now.
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