The Republicans of the 1850s-1860s were the anti-slavery party. Which is another way of saying they were the pro-black, pro-racial justice party of their time.
They also supported the national bank, railroads — big government projects designed to bring the nation together.
They had their base of support in the North (including cosmopolitan coastal cities) and the far-West.
And yes, they went to war against white supremacists.
Which modern Party does that remind you more of?