One of Abraham Lincoln's little-noted accomplishments has become his most unlikely legacy. He helped create the modern international rules that protect civilians, prevent torture, and limit the horrors of combat, the body of law known as the laws of war. Indeed, he was probably our most important law-of-war president, having crafted the very rules that George W. Bush and his Justice Department tried to destroy.
At the beginning of the Civil War in 1861, few Americans had given much thought to the laws of war. Lincoln was no exception. He had never been a soldier of any note. In middle age, he joked about his youthful service as a militia captain, observing that although he had fought and bled in "a good many bloody struggles," all his fights were with mosquitoes. As an Illinois lawyer, his bustling commercial law practice did not bring him into contact with the 19th-century laws of war, either.
When the shooting started at Fort Sumter on April 12, 1861, Lincoln became a war president barely a month into his first term in office. As a novice commander in chief, his inclination was to deny that the international laws of war had any relevance to the South's war of rebellion. The rebels were criminals, he insisted, not soldiers. Members of Congress and European statesmen pressed him to take international law more seriously. But Lincoln dismissed "the law of nations," as international law was then called, as a curiosity that country lawyers like him knew little about.
Lincoln's skepticism about the laws of war culminated a year later, in July 1862, in one of the Civil War's most famous early scenes. After weeks of deadly fighting and a demoralizing Union retreat in Virginia, Lincoln traveled to the front lines to encourage more aggressive action by Gen. George McClellan's Army of the Potomac. To win the war, Lincoln was beginning to think, the Union would have to attack the social fabric of the South. But McClellan resisted. The man known as "Little Napoleon" was one of the few Americans versed in the highly idealized rules of war handed down by the professional armies of 18th-century Europe. As McClellan saw it, the more aggressive campaign that Lincoln urged would undermine the European laws that had sought to make war resemble a kind of gentleman's duel.
Instead of embracing Lincoln's new urgency, McClellan lectured Lincoln on the laws of civilized warfare and the sharp constraints they placed on his prosecution of the Union war effort. A war among Christian and civilized people, he told the president, should not be a war against the people of the rebellious states, but a war between armies. He warned against the seizure of private property and especially against the "forcible abolition of slavery." Civilized wars, in McClellan's conception, left the fabric of society virtually untouched.
Lincoln grasped immediately that McClellan's conception of the laws of war would make it virtually impossible to win the war and preserve the Union. Just when a more aggressive war effort was required, McClellan was advocating rules of engagement that would have treated the South with kid gloves. At this same time, Lincoln was encountering a series of excruciatingly difficult problems that led him to reconsider his previous disdain for laws of war. On the high seas, the powerful nations of Europe demanded that the Union adopt a consistent set of predictable rules in its treatment of vessels from neutral foreign states. In the South, Jefferson Davis denounced Lincoln's decision to execute Confederate commerce raiders as pirates and threatened to retaliate in kind against captured Union soldiers. And in the West, guerilla fighting among civilians on both sides threatened to drag the conflict into a war of unremitting slaughter and destruction.
Most of all, Lincoln's increasingly firm conviction that the war needed to be brought home to the people of the South—and to the slave system on which they depended—cried out for new rules. After meeting with McClellan, Lincoln began to think about what advantages new laws of war might offer the Union effort.
The first stage of Lincoln's re-evaluation came in the Emancipation Proclamation. Less than a week after meeting with McClellan, Lincoln confided for the first time to members of his Cabinet that he intended to issue his controversial emancipation order. The proclamation was an utter rejection of McClellan's limited war model. But as Lincoln later explained it, his new view was that the laws of war authorized armies to do virtually "all in their power to help themselves, or hurt the enemy." Lincoln insisted that there were "a few things regarded as barbarous or cruel" that were beyond the pale. But there could be little doubt that Lincoln's Emancipation Proclamation would extend the war effort beyond the battlefield and into plantations across the South.
The second stage came that winter, soon after Lincoln finally fired the slow-moving McClellan. After appalling casualties on both sides at Antietam in September 1862 and in the midst of a devastating defeat at Fredericksburg, Va., in early December, Lincoln commissioned a new compilation of the rules for war. Written by a committee of veteran Union officers led by a professor at Columbia College named Francis Lieber, the code aimed to update the laws of war for modern conditions. It would enable the new, more aggressive war that Lincoln wanted to wage in the spring campaigns of 1863 while preventing aggressive modern warfare from sliding into total destruction.