Which states fought against slavery?

Answer 1

None.

The war was caused by the dispute over the admission of new territories, which the South wanted as slave-states and the North wanted as free soil. This did not have much to do with Abolitionism. It was really to do with keeping a Northern majority in Congress, so that they could continue to raise taxes on imports, and protect Northern industry. The South had almost no industry, so it was the South who would mostly be paying these taxes.

In the summer of 1862, it looked as though the British would be entering the war on the side of the Confederates, and Lincoln realized that if he officially turned the war into a crusade against slavery, the British could not intervene without looking pro-slavery.

The effect of his Proclamation was to allow his troops to rob the enemy of his property - which included slaves. It was clear that if the North were to win the war, these slaves could never be returned to their so-called owners.

So it was the war itself that liberated the slaves.