Then let's change this a little and instead of focusing on the South, let's look at what you accused it of :
First Claim: "The flag flew for the preservation and expansion of slavery."
It's not an accusation, its the fact of the matter and one to feel a measure of shame and sorrow over.
So Southerners, even plantation owners, did not speak of the freeing slaves?
Why does it matter? The South fought to preserve and expand the institution. That's, again, clear in the states individual declarations and it's clear among the letters written binding those states together by various ambassadors.
I'm giving this to show the end of slavery was Not foreign to the Southern mind.
From some and yet, as Lincoln notes, the actions of those in a position to do anything do much the same thing they always have.
Now whether the South could've or would've done away with slavery may be moot, but the question is whether you and others in agreement with you are right - that the Flag stood for what you say it did to the people who flew it?
It's rationally unquestionable. I gave you the declarations of the states themselves as they exited, of their ambassadors and noted the foundation of the war itself, a thing largely understood in its day.
And from my earlier and uncontested note with a bit of emphasis this time:
Here's South Carolina, the lead state in withdrawing from the Union:
...
A geographical line has been drawn across the Union, and all the States north of that line have united in the election of a man to the high office of President of the United States, whose opinions and purposes are hostile to slavery. He is to be entrusted with the administration of the common Government, because
he has declared that that “Government cannot endure permanently half slave, half free,” and that the public mind must rest in the belief that slavery is in the course of ultimate extinction. This sectional combination for the submersion of the Constitution, has been aided in some of the States by elevating to citizenship, persons who, by the supreme law of the land, are incapable of becoming citizens; and their votes have been used to inaugurate a new policy, hostile to the South, and destructive of its beliefs and safety.
Mississippi:
Our position is thoroughly identified with the institution of slavery—the greatest material interest of the world....
a blow at slavery is a blow at commerce and civilization. That blow has been long aimed at the institution, and was at the point of reaching its consummation. There was no choice left us but submission to the mandates of abolition, or a dissolution of the Union, whose principles had been subverted to work out our ruin…
Louisiana:
As a separate republic, Louisiana remembers too well the whisperings of European diplomacy for the abolition of slavery in the times of annexation not to be apprehensive of bolder demonstrations from the same quarter and the North in this country. The people of the slave holding States are bound together by the same necessity and determination to preserve African slavery.
Alabama:
Mr. Lincoln is hailed, not simply as it change of Administration, but as the inauguration of new principles, and a new theory of Government, and even as the downfall of slavery. Therefore it is that the election of Mr. Lincoln cannot be regarded otherwise than a solemn declaration, on the part of a great majority of the Northern people, of hostility to the South, her property and her institutions—nothing less than an open declaration of war—for the triumph of this new theory of Government destroys the property of the South, lays waste her fields, and inaugurates all the horrors of a San Domingo servile insurrection, consigning her citizens to assassinations, and. her wives and daughters to pollution and violation, to gratify the lust of half-civilized Africans.
Texas:
...in this free government all white men are and of right ought to be entitled to equal civil and political rights; that
the servitude of the African race, as existing in these States, is mutually beneficial to both bond and free, and is abundantly authorized and justified by the experience of mankind, and the revealed will of the Almighty Creator, as recognized by all Christian nations; while the destruction of the existing relations between the two races, as advocated by our sectional enemies, would bring inevitable calamities upon both and desolation upon the fifteen slave-holding states....
In 1860 Alabama sent men to other slave states do advocate secession. This from the pen of one of them, Stephen Hale in his letter to the Governor of Kentucky:
…African slavery has not only become one of the fixed domestic institutions of the Southern states, but forms an important element of their political power, and constitutes the most valuable species of their property…forming, in fact, the basis upon which rests the prosperity and wealth of most of these states…
It is upon this gigantic interest, this peculiar institution of the South, that the Northern states and their people have been waging an unrelenting and fanatical war for the last quarter of a century. An institution with which is bound up, not only the wealth and prosperity of the Southern people, but their very existence as a political community…
...Will the people of the North cease to make war upon the institution of slavery, and award to it the protection guaranteed by the Constitution? The accumulated wrongs of many years, the late action of the members of Congress in refusing every measure of justice to the South, as well as the experience of all the past, answers, No, never!
They weren't confused and you shouldn't be either.
This from Southern Punch in 1864, Richmond:
‘The people of the South,’ says a contemporary, ‘are not fighting for slavery but for independence.’ Let us look into this matter. It is an easy task, we think, to show up this new-fangled heresy — a heresy calculated to do us no good, for it cannot deceive foreign statesmen nor peoples, nor mislead any one here nor in Yankeeland. . . Our doctrine is this:
WE ARE FIGHTING FOR INDEPENDENCE THAT OUR GREAT AND NECESSARY DOMESTIC INSTITUTION OF SLAVERY SHALL BE PRESERVED, and for the preservation of other institutions of which slavery is the groundwork.