Doyle --
No real disagreement here. "The election of Lincoln in effect told the southern people that their Constitutional rights were not going to be respected."
"They knew exactly that the rule of law was not going to be observed."
That's exactly what many Southern newspaper writers were printing during the 1860 campaign. Most Southerners believed that they (as opposed to their Northern friends) were true supporters of the Constitution.
To return to the original question, I prefer to agree with those who say the war was about slavery in order to move on to issues that are more relevant to the conflict.