Lincoln was elected November 6, 1860.
South Carolina seceded on December 20, 1860.
Lincoln's election was no more the cause for secession than slavery; merely the catalyst.
The Constitution, at that time, did not allow the United States Congress to interfere in the states' internal affairs, which included slavery.
The Declaration of Independence states "That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Safety and Happiness."
Lincoln took office in March. Surely the reasoned gentlemen of South Carolina would not act without some overt unconstitutional act?
Or would they? Perhaps they had that time machine, or that special U-boat we have heard little SW talk about.
For the rest of us, we know the person who does something first, starts it. And bears the guilt for it.