An excerpt from the Georgia Declaration of Secession follows --
In the first years of the Republic the navigating, commercial, and manufacturing interests of the North began to seek profit and aggrandizement at the expense of the agricultural interests. Even the owners of fishing smacks sought and obtained bounties for pursuing their own business (which yet continue), and $500,000 is now paid them annually out of the Treasury. The navigating interests begged for protection against foreign shipbuilders and against competition in the coasting trade. Congress granted both requests, and by prohibitory acts gave an absolute monopoly of this business to each of their interests, which they enjoy without diminution to this day. Not content with these great and unjust advantages, they have sought to throw the legitimate burden of their business as much as possible upon the public; they have succeeded in throwing the cost of light-houses, buoys, and the maintenance of their seamen upon the Treasury, and the Government now pays above $2,000,000 annually for the support of these objects.
Theses interests, in connection with the commercial and manufacturing classes, have also succeeded, by means of subventions to mail steamers and the reduction in postage, in relieving their business from the payment of about $7,000,000 annually, throwing it upon the public Treasury under the name of postal deficiency. The manufacturing interests entered into the same struggle early, and has clamored steadily for Government bounties and special favors. This interest was confined mainly to the Eastern and Middle non-slave-holding States. Wielding these great States it held great power and influence, and its demands were in full proportion to its power. The manufacturers and miners wisely based their demands upon special facts and reasons rather than upon general principles, and thereby mollified much of the opposition of the opposing interest. They pleaded in their favor the infancy of their business in this country, the scarcity of labor and capital, the hostile legislation of other countries toward them, the great necessity of their fabrics in the time of war, and the necessity of high duties to pay the debt incurred in our war for independence. These reasons prevailed, and they received for many years enormous bounties by the general acquiescence of the whole country.
But when these reasons ceased they were no less clamorous for Government protection, but their clamors were less heeded-- the country had put the principle of protection upon trial and condemned it. After having enjoyed protection to the extent of from 15 to 200 per cent. upon their entire business for above thirty years, the act of 1846 was passed. It avoided sudden change, but the principle was settled, and free trade, low duties, and economy in public expenditures was the verdict of the American people. The South and the Northwestern States sustained this policy. There was but small hope of its reversal; upon the direct issue, none at all.
All these classes saw this and felt it and cast about for new allies. The anti-slavery sentiment of the North offered the best chance for success...
If you go on to read the rest, you find that there were three basic motives driving secession: the denial of the western territories to slavery, the refusal of the northern states to return runaway slaves, and the election of the abolition party to control of the federal government.
The party of Lincoln, called the Republican party, under its present name and organization, is of recent origin. It is admitted to be an anti-slavery party. While it attracts to itself by its creed the scattered advocates of exploded political heresies, of condemned theories in political economy, the advocates of commercial restrictions, of protection, of special privileges, of waste and corruption in the administration of Government, anti-slavery is its mission and its purpose. By anti-slavery it is made a power in the state.
The immediate cause of secession is Lincoln, the abolitionist. DiLorenzo may say that Lincoln was not an abolitionist, but Georgia saw him differently.
We had acquired a large territory by successful war with Mexico; Congress had to govern it; how, in relation to slavery, was the question then demanding solution. This state of facts gave form and shape to the anti-slavery sentiment throughout the North and the conflict began. Northern anti-slavery men of all parties asserted the right to exclude slavery from the territory by Congressional legislation and demanded the prompt and efficient exercise of this power to that end. This insulting and unconstitutional demand was met with great moderation and firmness by the South. We had shed our blood and paid our money for its acquisition; we demanded a division of it on the line of the Missouri restriction or an equal participation in the whole of it.
The greatest issue driving secession was control of the western territories.
The North demanded the application of the principle of prohibition of slavery to all of the territory acquired from Mexico and all other parts of the public domain then and in all future time. It was the announcement of her purpose to appropriate to herself all the public domain then owned and thereafter to be acquired by the United States. The claim itself was less arrogant and insulting than the reason with which she supported it. That reason was her fixed purpose to limit, restrain, and finally abolish slavery in the States where it exists.
They understood that denying slavers the right to westward expansion -as slavers- would undercut them and eventually bring about the end of slavery in the territories where it already was in place.
The Presidential election of 1852 resulted in the total overthrow of the advocates of restriction and their party friends....[I assume that refers to the collapse of the Whig party]... Immediately after this result the anti-slavery portion of the defeated party resolved to unite all the elements in the North opposed to slavery and to stake their future political fortunes upon their hostility to slavery everywhere. ...[That would be the rise of the Republicans]... This is the party to whom the people of the North have committed the Government. They raised their standard in 1856 and were barely defeated. They entered the Presidential contest again in 1860 and succeeded. ...[Lincoln}...
The prohibition of slavery in the Territories, hostility to it everywhere, the equality of the black and white races, disregard of all constitutional guarantees it its favor, were boldly proclaimed by its leaders and applauded by its followers.
With these principles on their banners and these utterances on their lips the majority of the people of the North demand that we shall receive them as our rulers. The prohibition of slavery in the Territories is the cardinal principle of this organization.
They go on to complain at length that the northerners are refusing to return runaway slaves, or to punish the underground railroad that is sheltering them.
And then finally: Such are the opinions and such are the practices of the Republican party, who have been called by their own votes to administer the Federal Government under the Constitution of the United States. We know their treachery; ....
...because their avowed purpose is to subvert our society and subject us not only to the loss of our property but the destruction of ourselves, our wives, and our children, and the desolation of our homes, our altars, and our firesides. To avoid these evils we resume the powers which our fathers delegated to the Government of the United States, and henceforth will seek new safeguards for our liberty, equality, security, and tranquillity.
They understood that having the abolition party in control of the federal government would ultimately bring about the end of their way of life, and they were probably right.
There are conflicts that are just going to be settled by arms, and this was one. The other Articles are even more explicit than this one in their defense of their peculiar institution. They were right in believing that they could no longer coexist with abolitionists. They were right in believing that they would never rest easy with abolitionists in the White House, and if they wanted to save their institution they had no choice but to secede.
The Whigs held many of the same opinions economically as did the Republicans, but they were not a threat; they may have opposed slavery but they were not sworn to end it. The Republicans were. That was all the difference.
It is one thing to argue the legalities of secession, and the constitutionality of a war to prevent secession. It is an interesting exercise. But that the war was about slavery, at least from the southern point of view, should not be in doubt, and that Lincoln was viewed in the south as the number one threat to slavery, even if Di Lorenzo doesn't see it, should likewise not be in any doubt.
There is a small irony here. For Lincoln it is about preserving the union, and he was willing to compromise on slavery to achieve it. For the south, it was about slavery, and they correctly understood that compromise or no, with Republicans in the White House, and expansion west cut off, they must secede or see their way of life overturned.