Rich man's war, poor man's fight.
After the Emancipation Proclamation, large numbers of Union soldiers wrote home to protest that ending slavery wasn't the reason they joined, either.
A common misconception is that throughout the North, people embraced the noble cause of fighting for the liberation of their fellow man.
You'd think so-called "Lost Causers" were the only ones clinging to a myth, wouldn't you?
Lets don’t leave out economics from this discussion. Lincoln was desparate to keep the South in the Union for the taxes on cotton which he couldn’t give up. His plan for the blacks was to either ship them all off to colonize a place in South America or parts unknown. He had no intention of leaving them in the USA.