Another major incentive was to keep Britain and France from recognizing and supporting the Confederacy. Making emancipation an explicit war aim was meant to move public opinion in those countries to support the Union.
“Another major incentive was to keep Britain and France from recognizing and supporting the Confederacy. Making emancipation an explicit war aim was meant to move public opinion in those countries to support the Union.”
That’s true. When Lincoln ordered federal troops to invade the nascent Confederacy in 1861 the emancipation of the slaves wasn’t even on his radar, and certainly was not a reason for the start of the War (and Lincoln said as much). Lincoln said his reason for going to war was to restore the Union.