Youre the only one that seems confused.
Your words....
"I said Lincoln went to war to save the union.
I later said as time went on his views on this changed"
Now youre saying...
"I said Lincoln's primary goal was to save the union and that slavery was a huge issue in the states."
Your going to have to get your story together and be more consistent.
Again someone writing a book has nothing to do with what the facts say. Lincoln could have cared less about slavery. Would you go to war over something you didnt care about and actually offered to the other side you went to war with in a effort to prevent said war?