For one to assert that slavery as practiced in the Old South was the one and only cause of our "War Between the States" (or, as some prefer to call it, "The War of Northern Aggression"!) will result in a failure to consider other very important aspects of American society both before and after the so-call "Civil[?] War."
This is not to say that some of the slaves in the Deep South were severely mistreated because they were. However, OTOH, many slaves were not "field hands." Many were "domestic servants" who were in some cases considered to be actual members of their "Slave-holder's Families."
Many of the original Black people from sub-Saharan Africa were not even slaves at all. They were more like "indentured servants" who were apprenticed to either plantation owners or other craftsmen who needed "extra hands" to assist them in whatever trade they practiced.
These "indentured servants" often lived with their "owner's" families, and some were even given in marriage to their "owner's" sons or daughters. Moreover, when armed conflicts did arise, these "indentured servants" often fought side-by-side with their "White 'Owners.'"
One also needs to keep in mind that many Northern families were also slaveholders--a fact that's often conveniently omitted in many history textbooks.
From our nation's early beginnings, the concept that the individual States had inherent rights and authorities that superceded those of the national government was quite evident in the writings of Presidents Jefferson and Madison respectively titled the Virginia and the Kentucky "Resolutions."
Moreover, the inclusion of the Tenth Amendment (often referred to as "The States' Rights Amendment") to our US Constitution's "Bill of Rights" (i.e., the first 10 Amendments) was very crucial to that document's ratification in many Northern AND Southern States.
Then, too, many states had to assume various burdens such as self-defense from foreign invaders that most folks today would consider to be something that our national government should have handled.
Also, to claim that President Lincoln was "The Great Emancipator" is to ignore the fact that he did little or nothing to truly "emancipate" the slaves that he actually had the authority to do so as soon as he assumed the Presidency in April, 1861.
Then, too, President Lincoln also practiced many other deeds that were directly in violation of our nation's Constitution's "Bill of Rights" (i.e., its first 10 Amendments).
The so-called "Emancipation Proclamation" wasn't issued until some three years until our "Civil[?] War," and it only really, as some historians point out, "freed what slaves he couldn't [i.e., those living in areas outside the control of the US {i.e., "the 'Union's' military forces}], while doing nothing to free the slaves that he could [i.e., those slaves living in areas that were under the control of the US {i.e., the 'Union's' military forces}]!!
In reality, it wasn't President Lincoln at all that supposedly "freed" the slaves. Rather, it was the 13th Amendment to our Constitution that wasn't ratified until December, 1865--almost a year and a half after Lincoln died from being hit by an assassin's bullet.
Moreover, to assert that the seceding Southern States were quite willing to return to the "Union" is to ignore other historical facts.
In reality, it was only because President-Elect Rutherford B. Hayes grudgingly agreed to end the era of "Southern Reconstructionism" in 1877 (some 12 years after the surrender of the Confederate forces under Gen. Robert E. Lee's command to "Union" Army's commanding general Ulysses S. Grant at Appomattox, VA).
Would an "Independent Southern States' Nation" have prevented some of the future events that some posters in this thread appear to claim that it would have?
I, for one, cannot say with any degree to certainty that it either would or wouldn't.
For my part, "Yours Truly" will leave that up to others who (apparently) have been given some sort of "prophetical insight" that I haven't been given.