Oh boy, this'll be fun.
The state of American politics back in the Civil War era wasn't a partisan divide so much as a regional divide. There were Northern Democrats who were unionist and anti-slavery, and southern Republicans who were pro-slavery. There were even *southern* Democrats (and Republicans) who were unionist and anti-slavery. It was messy and complicated. Families were torn apart, nowhere moreso than in the border states. Yes, Lincoln was a Republican, but protecting the Union was a team effort. It was Team Union vs. Team Confederacy. Conservatives who look back at the Civil War as a "Republican vs. Democrat" thing are projecting today's partisanship into the past.
During the Civil War, Lincoln issued the Emancipation Proclamation, and after the war, the U.S. Congress passed the 13th, 14th, and 15th Amendments, which were huge. However, a couple big caveats: (1) The Civil War wasn't fought primarily to end slavery, it was fought to restore the Union. Lincoln even said he would preserve slavery if it meant preserving the Union. Lincoln simply came to believe that ending slavery was in fact the best way to preserve the Union. (2) Lincoln himself (and most white Americans) personally thought blacks were inferior.
What followed the Civil War was "Reconstruction," a brief period where southern blacks had voting rights, and many black Americans were actually elected to state legislatures and Congress. But Southern racism reared its ugly head again, and Jim Crow laws began to sweep the South and again effectively disenfranchised black Americans on a massive scale. Confederate War Memorials began to be built several decades after the war ended, and the Confederacy began to be viewed as a noble "lost cause" rather than the treasonous and genocidal movement that it really was.
Believe it or not, Robert E. Lee was ashamed of his participation in the Civil War as a traitor, and wished that the War would never be commemorated. Those who wished to honor Lee's treason in spite of that didn't get the memo.
This was all a collaborative effort among Southern Democrats and Republicans who wanted to restore white supremacy, and Northern Democrats and Republicans who didn't care enough to stop it.
Oh boy, I haven't even gotten to the Civil Rights Era yet. Anyway, the 1960s once again brought a bipartisan effort to expand black Americans' rights against a bipartisan effort to oppose them. Republicans and Democrats weren't as sharply divided in the '60s either.
Caption this Meme 
