You might note that there were 5 Union states that all had chattel slavery throughout the war: Maryland, Delaware, West Virginia, Kentucky, and Missouri. The Federal capitol in Washington City had slavery when the war began, but abolished it in 1862...and appropriated $600,000 to repatriate their slaves back to Africa. Adjusted for inflation, that's about $60,000,000 in today's money.
Practically every officer in the Union army had servants. Grant was a slave owner through his wife, Julia Dent Grant. When Richmond fell, Julia was the only person allowed to be escorted through the streets of Richmond by her slaves and it was said that she openly flaunted it. The Grants did not emancipate their slaves until the ratification of the 13th Amendment in December 1865.
Early in the war, Grant gave a newspaper interview in which he said, "If I thought this war was to abolish slavery, I would resign my commission and offer my sword to the other side." Some Progressive historians try to claim that his enemies made that up, but that's false. It is a documented quote.
Union Gen. J.G. Foster was quite noted for his harem filled with "sable beauty".
The North was so desperate to keep their Southern tariff money coming in that they offered the
Corwin Amendment, which would have allowed the slave states to keep their slaves and promised that the Federal government would never bother slavery again if they would just return to the Union. It was not ratified only because the representatives of the Southern states were no longer present in Congress to vote on it. The Corwin Amendment was not sunsetted and technically remains open for ratification to this day, although it's been pretty much superseded by the 13th Amendment. The Corwin Amendment was supported by...Abraham Lincoln!
Some of the most ardent Unionists in loyalist East Tennessee were the largest slaveholders in that region. When Lincoln issued the Emancipation Proclamation, he exempted certain areas of Louisiana because one of his close friends owned a big sugar cane plantation there.
What made slavery such an issue was the fact that when an emancipation amendment to the Constitution was proposed, there had never been a constitutional amendment or provision that had ever granted the government the power to take away anyone's private property. If that power was granted, the concern was over further abuse of it and one only has to look at the problems that we have today over eminent domain.
If the Federal government was given the power to seize private property, where would it end? To see what the people of that time were thinking and what they were concerned about, you only have to look as far as the 14th Amendment.
The 14 Amendment granted citizenship to the former slaves. Nothing wrong with that and certainly the right thing to do. Right? Except that the way it was written, it created the problems that we have today with "anchor babies" and illegal immigration.
The people of that time knew something that we have forgotten today: laws can have unintended consequences, so you need to be very careful when you pass them.
Sorry, but your argument falls flat in the face of facts. There is revisionist history, but it's neither Southerners nor conservatives who revised it. All of these things were well known until the Progressive movement emerged in the early 20th century and started rewriting it, and the people who lived during the war and knew these facts gradually died off, allowing it to be forgotten.