The answer is: It depends on your point of view.
In regard to 'resolving the conflict peacefully' - The Southerners never fully believed initially that the North would go to war for the sake of abolition.
The issue of the day was: Did secession require an act of Congress to legalise it? The Constitution never mentions secession at all or even a perpetual Union. I believe this is what's referred to as 'state's rights' or 'compact theory'.
The belief was the various states delegated certain responsibilities to the central (federal) government, and everything else was pretty much left up to them. As the Constitution made no mention of the right to secede, and thus the States felt that annulling ratification of the Constitution was a legal right not delegated to the central government. Simply put, the Constitution made no explicit mention of secession, ergo that right rested with individual states.
The States did ratify their secession through the popular vote through electoral conventions held in early 1860 and 1861. So there was a legal and parliamentary procedure that was followed that was consistent internally with due process.
In regards to 'peaceful means' - the Confederate States had indeed hoped that the North facing of a difficult 'end state': fighting the Confederacy and occupying a vast amount of territory would simply be happy to see the slaveholding states go their own separate way. It was Lincoln at the urging of Douglas who categorised the secession as an 'attempt to overthrow the United States government'.
Was this tantamount to a declaration of war? Or was the occupation of Fort Sumter a declaration by the Confederates? Was the refusal of Union troops to relinquish what Confederates saw as their land an act of war? Whilst slavery is a charged issue, when you remove it from the equation, it's quite easy to see Lincoln as the aggressor. He mustered a large army, and in the early days of the war seemed intent on taking the offensive (despite how disastrous this turned out to be).
In a modern context (say Israel or Sudan) we would definitely consider the Northerners the aggressors. The Confederates were by popular vote now an independent entity and Lincoln was fully prepared to use force to bring them back into the fold. In regard to the legal argument (re: Act of Congress) the issue is: Did the States need Congressional approval? Given that the Constitution never expressly forbade secession one would lean towards, well, no.
It's ultimately a matter of perspective, though. I think a lot of Americans see the war as justified because of Abolition. However, the debate at the time was more about the preservation of the Union and states rights versus federal ones with Abolition being an important issue but not necessarily always the central one.
Source: The West Point History of the (American) Civil War
