But they didn't do that. They laid down their lives instead.
Like I said before, picking out only the things we dislike and overlooking positives isn't productive or honest to ourselves.
Only later did they free the slaves, and as an act of war more than freedom.
I don't think their primary motivation was preservation of the Union, I think it was abolition.
Let's not pretend preservation of the Union was the only major factor, or that abolition was entirely a back-burner concept, it had been building steam and popular support for decades.
Sure, preserving the Union may have been the main concern on a realpolitik level early on, but that doesn't change the fact that abolition was the writing on the wall and had been for decades.
No, because that’s what the Union said—that preserving the Union was more important than abolition. The South declared secession and attacked federal facilities anyway.
The South’s overweaning fear of the distant future possibility of abolition backfired and accelerated it.
It was only “its bloodiest war” because a sizable fraction of the country was fighting to protect slavery. Much of the rest of the world that had chattel slavery ended it without similarly bloody wars—and generally sooner. The fierce defense of chattel slavery in the US that produced its bloodiest war isn’t a positive.