Bryan,
Not sure of you intended for the sentence above to point only to the issue of slavery. I for one do not believe that slavery was the only issue involved in the act of secession or war. On this board we have discussed many issues including sectionalism, taxes, issues of the constitution, whether they were real or imagined and just the right of self government.
Secession solved the problem of slavery and or the expansion of because the South handed over all of the new territories to the United States. Lincoln then had the power to make motions to fully abolish slavery in the United States, without firing a shot, he chose not to. Lincoln never once said he was going to war to free any slaves. It has been posted to this board several times a letter from Lincoln that would allow the seceding states to return to the Union and keep their slaves. If the issue was slaves surely they would have taken this offer.
I am not so sure that secession can be sited as "the" cause of the war either. I say this because I haven't had the chance to locate any huge outcry from anyone anyplace demanding Lincoln bring the seceding states back to the Union. Was there any? If not then it would appear to me that Lincoln went to war to sooth his own bruised ego and those politicians around him. Lincoln's cause is well known to be "save the Union" did that mean he would not have the power of his office and his cabinet challenged? Did that mean he would not have the voting process of the day challenged? Did he so strongly believe in the idea of a strong central government that he chose to make war to prove that point?
I believe that we have been steered down the narrow corridor of slavery--secession so long that we just do not or will not see the other possible causes of the war.
GP