Answer: This sentence advance Lincoln’s viewpoint through demonstrating
Lincoln feels one side placed personal interest before the good of the country as a whole, while the other side was willing to fight to keep the country intact.
Explanation: Lincoln begins by acknowledging that neither side DISAPPROVED of war (deprecated), yet one side was willing to make war instead of preserving the nation (Confederate South) and the other was willing to have war to preserve the nation and disregard Southern secession requests (North).