All the movies about Lincoln are propaganda meant to justify his actions. I've never been much concerned about the Civil War, but I have been researching it this last year, and I've discovered it was not fought over slavery, it was fought over who was going to control the profits created by slavery.
New England was making a fortune off of Slavery, and an independent south threatened that money stream. What tipped me off to the real story is this map created by a anti-confederate website. (deadconfederates.com) It was a real eye opener.
See that pile of coins on New York? Those are the tariffs collected on European trade, so the dollars that went through the New York economy were much greater than that pile of coins indicates.
3/4ths of that money came from Slavery. When the South moved for Independence, the bulk of that money would be lost to New England, and *THAT* is why the power brokers of New England pushed Lincoln into launching a war to stop the South's move to become independent.
Southern independence threatened too many rice bowls of powerful men.
The "We were fighting to free the slaves!" spiel was just propaganda to misdirect the dupes regarding their real reasons. Lincoln clearly stated he was not going to end slavery if the Southern states would stop fighting and rejoin the Union.
Of course he wasn't going to end it, because his New York backers wanted to get that money stream going again, but after awhile, it became impossible to restore things to the way they were. They had spread that propaganda for too long, and now it was expected that they would live up to it.