Slavery has never been Constitutionally protected. It was a point of Stephens during the Cornerstone Speech, that the old Constitution didn't, the Founders didn't understand, and the new CSA constitution did protect slavery, not just as a right bus as the "proper place of the negro." The 13th doesn't come about until after the Civil War, and it forever ended slavery as a legal institution in the USA. But, as history shows us, whiney CSA snowflakes wouldn't have it, broke many laws, became terrorists, birthed the Klan, and couldn't bear the thought of a black person walking and living free, so they found additional ways to repress and oppress.
I see you haven't read the posts I asked you to. If you had you wouldn't have made the mistake of saying slavery was never protected by the Constitution. Please read them as it would help. (42,56,62,64,67,69)
Slavery was protected by the Constitution in the 4th amendment. Any escaped slave was to be returned to his rightful owner. The original 13th amendment was offered to the South by Congress and endorsed by Lincoln after the first 7 states seceded. It was promised in hopes that the South would not secede. It made slavery perpetual in the U.S. with the assurance that no law could be passed against it. It was rejected by the South. Thus it never came into being.
Prior to this offer of the 13th amendment, was the Dred Scott decision. As I have pointed out in the posts I mentioned, it was a Supreme Court case. As you know, or should know, the Supreme Court deals with Constitutional Law. To be brief, the Supreme Court decision removed the division between free and slave states, doing away with the Missouri Compromise.
What did this mean? It meant the Southernor was free to take his slaves in any state or territory he wanted and was protected by the Constitution.
Your last sentence shows the shallowness of your knowledge of the War between the States. You just offer the simple buzz words based on emotion. The typical waving of the bloody flag.
Do your research on the things I have mentioned and show me where I am historically mistaken.
Good-Ole-Rebel