Lincoln preserved The State ... not the States.
I think TM7s passing comment was interesting in that Lincoln may have felt it was worth abandoning the republic to build a stronger union in the face of external forces. Sort of a lesser of two evils decision ... that would be charitable on Lincoln's behalf, and begs the question, would we have been better off if the Confederation had been successful in protecting their independence? Are we would now be much like a fragmented Europe, and worse for it? All that said, we can definitely see the erosion of liberties accelerating in earnest in the wake of his term in office, so perhaps Lincoln himself would regret his decision in hindsight.
A modern analogy might be Saddam Hussein, a tyrant who has been the only person to keep warring internal factions at bay, protect his homeland from 2 possibly 3 foreign incursions, all the while creating wealth for his nation and preserving religious freedom for all, 5th largest army, high education levels ... A tyrant, absolutely, and ruthless, personally shooting his opposition and worse. Yet when we withdraw (some day), individual Iraqis will have less freedoms, less wealth, and be far more susceptible to external influence in our wake (this is concurred by all parties). Not saying Saddam was THE answer, just AN answer that worked ... and that'll be discussed for generations to come. So Lincoln may have been a tyrant, and undeniably repressed the liberties of many for a time, and set the stage for future infringement of all, but one wonders what the alternative might have been. Personally, I would've like to have seen it just on the principle of state sovereignty but I am one who is unafraid of the risks involved with right choices. Our society is not.