I recommend you take a look at the FAQ, specifically here: https://www.reddit.com/r/AskHistorians/wiki/civilwar

Slavery was entirely the cause of the war. Slavery shaped the economy of the South, slavery split the congress, the electorate and, ultimately, the nation.

The linked article is nonsense. What little of it is coherent is wrong or misleading. I'll quote the "justifications," then answer them, but I'm not sure how far I'll make it. Wow, that formatting.

Anyway, let's take a walk.

"Also, the Northern states were taking advantage of their superior numbers in the federal government and were using their advantage to implement unfair tariffs against the South. Enormous amounts of money were taken from the South and funneled into the Northern states.

The North was taking advantage of their superior numbers, which yeah, that's not great if you're one of the inferior numbers, just ask Maine every time they're not California. What was the North doing with this numerical superiority? Invading? Electing a Frederick Douglas president? Forcing Alabama to wear a funny hat?

Oh. Tariffs. Huh.

The "unfair tariffs" are probably the Morrill Tariff but I'm not sure. Way to cite, Sons of Confederate Veterans. Anyway, the Morrill Tariffs did indeed favor the North because they set a tax on imported European goods, which in turn encouraged domestic manufacturers. This is what tariffs are for. The South didn't like the idea because they had very little industry and most of their economy was export-based. The export was largely cotton and most of it was sent to Europe. The South was worried the tariffs would reduce demand for their cotton. Cotton grown by slaves.*

Tariffs. All those young men dead and maimed while nobly trying to get an import tariff revoked.

"The South fought to preserve the Union as it had been created by their forefathers and when the Northern interest so warped the US Constitution, the only honorable thing left for Southern political leaders was to leave the US and form its own Confederation."

That Confederation only left the union because it was unhappy about the results of a Presidential election. And why were they unhappy? Well, let's ask South Carolina. Here they are, in their own words, with some notes by me:

_"A geographical line has been drawn across the Union [dividing slave states and free states], 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 [that would be Lincoln, say not his name]. 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," [say not his name, but quote him] 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 [that is, black people]; and their votes have been used to inaugurate a new policy, hostile to the South, and destructive of its beliefs and safety."_

Funny. In South Carolina's justification to the world for their succession from the union, the word "slave(ry)" appears eighteen times. The word "tariff" is nowhere to be found.

I can't do anymore. My typing fingers are sad.

*: But poor southerners didn't own slaves! They grew their own cotton!

Sure, but poor southerners didn't make the choice to leave the union. That choice was in the hands of rich Southerners.

The link is a classic case of confirmation bias posing as history. It is very easy to find quotes where the South claims the righteousness of its cause, and then pretend that those quotes are reality instead of self-serving propaganda.

In reality slavery was the primary cause of the war, as admitted by the Southern states themselves when they declared their intent to secede:

http://www.civil-war.net/pages/southcarolina_declaration.asp

Some choice bits:

But an increasing hostility on the part of the non-slaveholding States to the institution of slavery, has led to a disregard of their obligations, and the laws of the General Government have ceased to effect the objects of the Constitution.

Note the use of the word slavery and how the non-slave states were supposedly attacking it... despite the fact that Lincoln had not even taken office yet and Lincoln promising not to abolish slavery; only to prevent its extension into the territories during the election campaign. In addition, the word "tariff" appears nowhere in this document, which is unsurprising because "Lost Cause" propagandists invented the tariff issue long after the war to hide the fact that the Confederates they worshiped were greedy and immoral slavers.

Funnily, the document itself is rife with double speak and confirmation bias. For instance it quotes the Declaration of Independence here:

In the year 1765, that portion of the British Empire embracing Great Britain, undertook to make laws for the government of that portion composed of the thirteen American Colonies. A struggle for the right of self-government ensued, which resulted, on the 4th of July, 1776, in a Declaration, by the Colonies, "that they are, and of right ought to be, FREE AND INDEPENDENT STATES; and that, as free and independent States, they have full power to levy war, conclude peace, contract alliances, establish commerce, and to do all other acts and things which independent States may of right do.

Which supposedly supports the idea that the individual states in the US were supposed to be independent (which isn't supported by the Treaty of Paris in 1783 which actually confirmed American independence, but I digress). The thing is, the most famous line in the document quoted, the Declaration of Independence, was in fact this:

We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.

So how exactly can South Carolina and the rest of the Confederacy pretend to be upholding the declaration of independence when they created a state where slavery was legal and men are in fact not created equal within its borders?

The Confederacy's legal and moral position in fact is little more than a mass of self-serving contradictions, that easily falls apart with some basic research. They were rebels who wanted to subvert American democracy with an aristocratic slave plantation system premised on the exploitation of their fellow men; and they were willing to hide behind whatever flowery words would seem to justify their morally bankrupt position.