Look, I am not going to argue this point too awful much here, but this is a singular viewpoint, and to play the devil's advocate... the last slaves were not freed till two YEARS after the Emancipation Proclamation, which only freed the slaves in the "Rebel States." This means it was solely a political move meant to engender rebellion and sow chaos on the opposing side of the conflict by inciting riots among the slave populationsm.
Lincoln actually wrote in a letter to Horace Greely in August of 1862, "My paramount object in this struggle is to save the Union, and is not either to save or to destroy slavery. If I could save the Union without freeing any slave I would do it, and if I could save it by freeing all the slaves I would do it; and if I could save it by freeing some and leaving others alone I would also do that. What I do about slavery, and the colored race, I do because I believe it helps to save the Union; and what I forbear, I forbear because I do not believe it would help to save the Union."
Slavery was not his concern in this, he didn't care if the slaves were free or still slaves hence why slavery continued in the northern states unabaited for two years after the ened of the war, and effectively the nation continued slavery through Jim Crow laws involving property, voiting rights, legal rights and other unfair treatments of black people, till 1902! Also don't forget that Blacks were not the only "slaves" in America at the time, Irish Americans were coming over on the boats as indentured servants, and the Chinese/japanese workers were often taken by force into such a life from the ports of Shang Hai, and Tokyo.
I do agree that the impact of slavery in the war has been marginalized by groups such as the sons and daughters of the confederacy, however, such organizations as the NAACP and things like BET television can be just as divisive and damaging. If you want a truely homogenous melting pot them we need to all accept that we have Heritage, and that we have race, and that it is OK to have pride in that, no matter which one that you happen to belong too. White people are still the majority, but that isn't going to be the case much longer. The last year saw the percentages in the census drop to 61%, the lowest ever measureed in the USA.
Unfortunately, and I hate to say this, the 1960s white supremacist had a point. If one group is discouraged from having a racial identity and the others encouraged to embrace their own, then which group is going to have an identity when it is all said and done.