We went to see the movie Lincoln after Thanksgiving dinner. It's a good movie, I highly recommend it. I knew it was going to be good early on when there's a scene in which it is established that the reason the Confederacy went to war was to preserve slavery. Full stop. None of this "well there were other circumstances" stuff.
And the movie makes it clear at the end too - when Lincoln is meeting with the Confederate representatives who were looking to figure out a peace accord, the Confederates suggest that they would join the Union again only if it would give the slave states a chance to prevent ratification of the just-passed 13th Amendment abolishing slavery.
When Lincoln points out to them that two or three of the Confederate states were likely to ratify - enough for it to become law - it's clear that the Confederacy will fight to the bitter end. Because they loved slavery so much.
Turns out it is especially appropriate to see a movie about Lincoln on Thanksgiving because he was responsible for making it a national holiday:
Thanksgiving was first celebrated on the same date by all states in 1863 by a presidential proclamation of Abraham Lincoln. Influenced by the campaigning of author Sarah Josepha Hale, who wrote letters to politicians for around 40 years trying to make it an official holiday, Lincoln proclaimed the date to be the final Thursday in November in an attempt to foster a sense of American unity between the Northern and Southern states.[25] Because of the ongoing Civil War and the Confederate States of America's refusal to recognize Lincoln's authority, a nationwide Thanksgiving date was not realized until Reconstruction was completed in the 1870s.