Something we agree on.They fought the North over states' rights. Again, the North only decided to push to end slavery when they discovered that it was a potential economic boon to the South that the North couldn't leverage as well. There was no moral outrage, it was all about the North wanting to keep the power in the country and they saw that the South was an emerging economic powerhouse.
Many Northern states had slavery legal until the 1850s or so.
They didn't care. When they were building the Erie Canal, they started using Irish, and switched to black slaves because it was too dangerous and they were paying too much death benefits to Irish widows.
It was purely economics.
The Union did the typical Anglo thing, and cloaked their naked ambition with some moral pretext.