One of the most important legacies of the American Civil War, not just in the re-united States of America but also in the nineteenth and twentieth century world, were the new laws of war that the conflict introduced. “Lieber's Code,” named after the man who authored it for the Lincoln administration, was a set of instructions written and issued in April 1863 to govern the conduct of “the armies of the United States in the field.” It became a template for all subsequent codes, including the Hague and Geneva conventions. Widely understood as a radical revision of the laws of war and a complete break with the Enlightenment tradition, the code, like the war that gave rise to it, reflected the new post-Napoleonic age of “people's wars.” As such, it pointed forward, if not as the expression of the first total war, then at least as an expression of the first modern one, with all the blurring of boundaries that involved.
A Study on the Character of the Civil War - Focusing on the Total War -