That is a little weird.
Yes, the reality of the civil war WAS a state’s rights issue. It was more than just land though. It was also the regulation of interstate commerce.
We do the same thing today to justify wars. Slavery was used to justify war against the states.
Do some research and you will find that prior to the CW the Feds were used to set up courts to sell the land. After the CW the Fed held onto that land. That and the fraud of making states which did not qualify as states makes the conclusion obvious.