If Lincoln is among history's truly great men, he didn't achieve that stature until his final three years. This was when his long-held antipathy to slavery cohered into a dedicated hostility that gave larger purpose to the Civil War and also confirmed the logic of Lincoln's destiny.
Struggling to end the war and to eliminate slavery once and for all by way of the 13th Amendment, with the amendment's prospective passage undermining the effort to make peace with the Confederacy and vice versa, Lincoln embodied the Great Man theory that leftists disdain.