The Civil War should have made it clear to the rebellious Southern States that those that lose at the legitimate ballot box, should suffer greatly for their resort to arms against their lawful National government, and to a certain extent, those in the south did indeed suffer greatly for this civil war, but rather disappointingly it did not take long for those of the upper echelons of southern power and class, all white, to once again take the reins of their States, and to specifically assert their sovereignty over their respective States, in which, though the Federal government had passed specific Constitutional amendments, granted all citizens, irrespective of their class, race, or former servitude, full Constitutional rights, that in effect, these were dead letters within these States, to the disgrace of the National government, tarnishing the last full measure of devotion given by the Union cause, but in an era in which States had significantly more sovereignty than they have today, not completely unexpected.
The problem that the white elite of the south had, after their ignoble defeat, was that they lived in a society, surrounded by a massive multitude of "freed" black men, women, and children, that they were no longer legally allowed to enslave, in which these former slavers, were aware of their freedom, but lacking property, education, and employment, blacks were still quite exploitable by those agents of the State. For, if the power within a given State, is held in the combination of the policing arm, the justice arm, and the employment arm, in an era in which a significant amount of wealth was created through agricultural efforts, than those certain people, fused in purpose, could still create a society in which though blacks would no longer be slaves, they would still be subservient to the purposes of those that controlled their freedom, with nowhere for blacks to turn to for sanctuary.
This meant that blacks were subject to all sorts of specific laws, known as "black codes", and blacks that were needed to labor in the fields, were often put into a position of powerlessness, in which, their options came down to either working in the fields under the most unfair of labor contracts or suffer imprisonment for vagrancy or similar, and even being in prison, would still mean working in the fields, as uncompensated forced labor. No matter how it played out, because blacks had no power as well as no voice, they were stuck in an endless cycle of work in which their labor was never paid enough for them to have any real property of their own, with nowhere to go, nowhere to escape, and since they were no longer owned as property, were treated with even more disdain by their white overlords, since they now had less obligation or reason to take care of them.
All of the above basically means, that it doesn't much matter what the law of the land says or means, if in effect, those that are supposed to benefit from it, or to be protected by it, do not. Further to the point, those that are defeated should never be allowed to have meaningful places, once again, in the power places of their community, for a leopard does not change its spots, and therefore a mere pledge of allegiance to the United States of America, from an unrepentant Southerner was effectively as hollow as their self-delusional Lost Cause.