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.
The code reduced the international laws of war into a simple pamphlet for wide distribution to the amateur soldiers of the Union army. It prohibited torture, poisons, wanton destruction, and cruelty. It protected prisoners and forbade assassinations. It announced a sharp distinction between soldiers and noncombatants. And it forbade attacks motivated by revenge and the infliction of suffering for its own sake. Most significantly, the code sought to protect channels of communication between warring armies. And it elevated the truce flag to a level of sacred honor.
In the spring of 1863, Lincoln's code was given not just to the armies of the Union but to the armies of the Confederacy. The code set out the rules the Union would follow—and that the Union would expect the South to follow, too. For the next two years, prisoner-exchange negotiations relied on the code to set the rules for identifying those who were entitled to prisoner-of-war status. Trials of Southern guerilla fighters and other violators of the laws of war leaned on the code's rules for support. The Union war effort became far more aggressive than it had been under McClellan's rules. As the Union's fierce Gen. William Tecumseh Sherman put it, Lincoln brought the "hard hand of war" to the population of the South. But this more aggressive posture was not at odds with Lincoln's new code. It was the code's fulfillment.
As the code's Confederate critics noticed immediately, the laws of war Lincoln announced in 1863 were far tougher than the humanitarian rules McClellan had demanded a year earlier. The code allowed for the destruction of civilian property, the bombardment of civilians in besieged cities, the starving of noncombatants, and the emancipation of civilians' slaves. It permitted executing prisoners in cases of necessity or as retaliation. It condoned the summary executions of enemy guerillas. And in its most open-ended provision, the code authorized any measure necessary to secure the ends of war and defend the country. "To save the country," the code declared, "is paramount to all other considerations." Lincoln's code was a body of rules not for McClellan's gentleman's war but for Sherman's March to the Sea.
In the decades after the Civil War, Lincoln's rules went global. International norms become international law only when great powers agree to comply with them, and Lincoln's code seemed to allow the great powers of the world to prosecute war aggressively without descending into wars of total destruction. Translations of the code spread through the armies of Prussia and France and into multinational treaties signed at The Hague. Following World War II, its provisions reappeared in the Geneva Conventions that are in effect to this day. Eventually, Lincoln's code would make its way into the pockets of men and women stationed around the world, in the field manuals and wallet cards that soldiers carry with guidelines for the laws of armed conflict.
Yet if soldiers still today carry around a little bit of Old Abe Lincoln in their pockets, the appeal of his approach to the laws of war has waned in recent decades. Today, the two leading paradigms for the laws of war are a humanitarian model and a war crimes model. The former would base the laws of war in individual human rights, the latter in the criminal tribunals like the one at Nuremberg after World War II.
In 1862 and 1863, Lincoln was up to something very different. His personal passage from law-of-war skeptic to law-of-war reviser in the midst of the Civil War offered him a distinctive vantage point. His code sought to organize the laws of war not around individual human rights or war crimes trials, but around reciprocity and coordination between armies. Lincoln's code set limits on his army's conduct, to be sure. But it also aimed to win a war. The function of Lincoln's laws of war was thus to identify and protect opportunities for cooperative behavior even in the clash of armed conflict.
In our own time, Lincoln's pragmatic model of the laws of war can help us in Iraq and Afghanistan. There is little prospect of reciprocity with terrorists, of course. But if one thing has become apparent in the cross-border security threats of the 21st century, it's that cooperation among the decent states of the world will be indispensable to policing against common threats. This is what Secretary of State Hillary Clinton meant when she stated in her confirmation hearings, "Today's security threats cannot be addressed in isolation." Combating terror, according to Clinton, requires "reaching out to both friends and adversaries, to bolster old alliances and to forge new ones." Lincoln's laws of war did just that. They were ways of reaching out to bolster cooperation even in the midst of conflict.
For the past seven years, America has repeated the journey Lincoln completed in 24 grueling months. Strong majorities of Americans now call for the dismantling of detention facilities at Guantanamo. Even stronger majorities oppose the use of torture in interrogations. As a nation, we have walked in Lincoln's footsteps, down an uncertain path from skepticism about the laws of war to a rediscovery of their pragmatic mix of toughness and humanity. President Obama, in his inaugural address, pledged to reconcile our interests and our ideals. This is precisely what Lincoln's laws of war sought to accomplish, rejecting lawlessness while relentlessly pursuing threats to our way of life.