What most here don’t want to dig into is the fact that Lincoln’s motives were not as pure as the driven snow. He cared nothing for freeing slaves. I suspect that northern interests were interested in holding the south as a sort of colony which could provide cheap labor and resources for their industrial system as well as a market for its products. The government likely saw secession as a loss of an enormous tax base.
...but the northerners got the advantages of cheap labor. As always with war, a bunch of northern businessmen made a bunch of money while a bunch of people died.
The only part of your statement I disagree with is that I think Lincoln was interested in freeing the slaves.....and deporting them.
You are right about the deportation. Few whites, north or south saw blacks as any semblance of equals. The normal practice was to return escaped slaves to the south. A “free state” mostly meant that a slave could become free if someone bought his way out, not that he was automatically free once he got there.
We know little of historical motives, and have been taught mostly BS.