Democrats have been so successful in playing the Race Card against Republicans that some Republicans have come up with the idea of playing the Race Card Right Back - in hopes liberals will vote for the GOP.
That's not going to work for several reasons. For one thing, a lot of people are aware that Lincoln was a white supremacist. And people are generally aware that post-war northerners got very friendly very quickly with Jim Crow - segregation of races in the South by law and custom; segregation of the races in the North by custom and sometimes by law.
Oh yes, the North had the troops but they abandoned their supposed black allies quicker than you can say “Lincoln fought to free the slaves.”
Wow. If you're that down on Lincoln for white supremacy and the North for racial discrimination then you must really hate the Confederate leaders and the South in general for those very same reasons.
According to today’s standards most Americans were white supremacist’s in the 1860’s. Abolitionist who believed in equality between the races were a very small minority. However, there is a huge moral chasm between Abraham Lincoln’s views on slavery and the southern leaders views on slavery.
As far as your second point, and I can’t believe I’m saying this, I actually agree that it is shameful that the north, and the Republican Party, abandoned the freedmen to the tender mercies of southern whites. It would take over 100 years for blacks to finally be able to exercise their basic constitutional rights.