Again.
Prior to the war, Election of 1860, Democrats divided into two factions (North and South) over the issue of slavery, each running their own candidate for president.
During the Civil War, Northern Democrats divided into two factions yet again, the War Democrats supporting Lincoln's military policies and the Copperheads who were against them. The Southern Democrats faction disappeared as the Confederacy OUTLAWED political parties.
After the war, the Democrats, as they had for years, looked at slavery as an issue to be decided by individual states. It wasn't a party-wide support for the institution, but support for states' rights, and the Democrats had favored that over big goverment federalism since their inception.
Lincoln wasn't alone among Republicans in his publically professed racist attitudes and pro-segregationist if not pro-deportation advocacy. They were no more for equal rights than anti-hunting activists are for deer taking over their yards to feast on their cute azaleas and tomato plots. They didn't see slaves as people who should be treated as civilized equals, they saw that as civilized people they shouldn't be treating others as slaves.
And again, voting for these rights was divided between North and South lines, not political parties. In 1880s Texas the Lily-White Republican Movement was born. Look them up for the lulz.
By conceding to their lie you're verifying their lie.
#therewasneveraswitch