This essay from the Times Literary Supplement (23 May 2003) reviews books on Lincoln's speeches and writings, particularly the Second Inaugural Address. It examines the transition from the First Inaugural Address to the Second Inaugural Address, finally focusing on how Lincoln seeks to steer between moral relativism about the war - each side does as it sees right - and moral absolutism.
Anderson, Kenneth, "To Finish the Work We are in: Abraham Lincoln's Speeches, from Lawyer's Briefs to Moral Manifesto" (2003). Book Reviews. 50.