Lincoln didn't consider the southern states as having the right to secede.  You could say, he forced the issue, creating a shooting war that he always stated was to "Preserve the Union"...had he recognized the south as having left, he would have fought to "reunite" the union, not "preserve" it.  At that point in American history, people valued their connection to the STATE much more than to the federal government.  Look at the units that made up BOTH sides of the fighting...they were raised by STATES!  The federal government was seen then (as it is seen now) as to be overreaching in its authority and power.  Trampling on the 10th amendment.  If you were a free black in the south, and a large property owner, you TOO would own slaves.... It was an economic issue to the south...and a State's rights issue.  (And even when the feds passed a law like the fugitive slave act, they were seen as weak and unable to enforce it!)