Paths to the Present


Civilizing Civil War: The Nineteenth Century

The address by Abraham Lincoln (1809–65) at the dedication of the Soldiers’ National Cemetery on November 19, 1863, may be the best-known speech in American history. Lincoln located his words precisely in time and space: eighty-seven years after the Declaration of Independence, he delivered them on a “great battlefield” at Gettysburg, Pennsylvania, from which they have always been called the Gettysburg Address.

Fourscore and seven years ago our fathers brought forth, on this continent, a new nation, conceived in liberty, and dedicated to the proposition that all men are created equal. Now we are engaged in a great civil war, testing whether that nation, or any nation so conceived, and so dedicated, can long endure.1

Lincoln’s plangent eloquence and hard-won brevity on that day have inspired more commentary than has any other text in American history except the declaration itself and the U.S. Constitution. Almost all of the address’s 272 words have been inspected minutely, except for the most chilling, his description of the ongoing conflict in which the dead had fallen at Gettysburg as “a great civil war.”2 The speech may be familiar, perhaps even too familiar, but the meaning of all its words is not as clear as it might at first seem.

Lincoln could not have known that he was speaking at almost the midpoint of what would be the most costly military struggle fought on North American soil. The conflict had begun two and half years earlier in April 1861 with the Confederate bombardment of Fort Sumter in South Carolina; it would grind on almost as long to its formal conclusion with the surrender of the Confederate general Robert E. Lee at Appomattox Court House in April 1865, though that act hardly brought hostilities to an end.3 The war was surely “great” in terms of the lives lost, the costs endured, and the stakes for each side, for the African Americans caught between them, and for the wider world. No one, enslaved or free, participant or observer, Northerner or Southerner, Unionist or Confederate, could disagree about that. But that this great struggle was a “civil” war was less certain when Lincoln spoke at Gettysburg than it is now, in the long aftermath of the Union victory.

Only six months before the Gettysburg Address, the Union army had received copies of General Orders No. 100, the legal code for the conduct of war drafted by the Prussian-born American lawyer Francis Lieber (1798–1872). That document was not produced in the context of a conventional war between nations, but it still carried the marks of traditional conceptions of war and of civil war. This was especially true of Lieber’s definition of civil war in the Code. He was mindful that Vattel had thrown down a challenge, over a century earlier, for any such legal description, a challenge that his own superior, the Union general (and international lawyer) Henry Wager Halleck (1815–72), had later taken up in refuting Vattel. Lieber’s own legacy on the question of civil war is distinctly ambiguous: the Code would endure, in U.S. military circles and in the foundations of international humanitarian law in the twentieth century. At the same time, however, his conception of civil war was internally contradictory and inapplicable to the conflict at hand. It was also irreconcilable with Lincoln’s implicit understanding of a “great civil war,” uttered amid a struggle that would become a paradigm of the relationship between secession and civil war.

We should be suspicious by now that the words “civil war” could ever be used without political intent or ideological baggage. Following the age of revolutions, civil war was supposed to have become an illegitimate form of struggle, a throwback to the turbulent rule of kings or to the recurrent instability of republican Rome—an ancient curse that enlightened modern times had lifted. Some did not think so. For example, the mid-eighteenth-century French republican the abbé de Mably (1709–85) has an English “Milord” in his dialogue The Rights and Duties of the Citizen(1758) shockingly state that “civil war is sometimes a great good,” for it can act as a surgery to remove a gangrenous limb that could destroy the body politic.4 The early Spanish liberal politician Juan Romero Alpuente (1762–1835) likewise argued in a speech of 1821 that “civil war is a gift from heaven,” offering a chance for national renewal—a phrase that would echo through Spanish history into Spain’s civil war in the twentieth century.5 And in 1830, the French politician and memoirist the baron de Chateaubriand (1768–1848) mocked those “lovers of humanity who, in armed quarrels, distinguish species and faint at the very name of civil war: ‘Compatriots who kill each other! Brothers, fathers, sons confronting one another!’ All this is no doubt very sad; however, a people is often strengthened and regenerated by internal discords.”6 Civil war might still be just in the eyes of those for whom it is necessary. But as ever, the question was who decides it is necessary and when to call it a civil war.

If civil war was not yet obsolete, it was also, perhaps anachronistically, unregulated. Thinking about it had not kept pace with the age’s systematic approach to so many other phenomena. Between the mid-eighteenth century and the mid-nineteenth century, the moral and political questions raised by revolutionary civil wars made ever starker the lack of a theoretical—and, especially, a juridical—framework for restraining and ultimately civilizing it. This was largely because civil war had for so long been written about by historians and poets rather than by philosophers or social theorists.7 Civil war challenged some of the most basic definitions of war, because the modern definition of war was a conflict between established sovereign entities—states—not a conflict within them. Jean-Jacques Rousseau offered this classic definition in his Social Contract(1762): “War is…not a relationship between one man and another, but a relation between one State and another…any State can only have other States, and not men, as enemies.” Individuals, in other words, cannot be the enemies of states, because they “are enemies only by accident, not as men, nor even as citizens, but as soldiers”; if they are inimical to one another, they cannot be engaged in war.8 By these lights, civil wars were not “wars” at all, because the parties were not confined to states and the combatants could not all be soldiers, that is, legitimate belligerents authorized to fight by a sovereign.

The greatest of all modern works on warfare, Carl von Clausewitz’s On War (1832), never mentions civil war.9 As mentioned earlier, there is no great work of strategy titled On Civil War, even as a parallel to Mao Zedong’s or Che Guevara’s works on guerrilla warfare.10 Clausewitz’s contemporary rival in the theory of war Antoine Henri Jomini (1779–1869), a Swiss officer who had served with the French army, does admit civil wars and wars of religion. But he concedes, “To want to give maxims for these sorts of war would be absurd.” This was because he viewed these as wars of “opinion”—or, as we might now say, wars of ideology—and as such more destructive and cruel than wars of policy, because they are more irrational.11 Such attitudes prevented the extension of the original Geneva Convention (1864) to civil wars: “it goes without saying international laws are not applicable to them,” asserted one of the Convention’s original drafters, Gustave Moynier in 1870.12 The challenge facing Lincoln and Lieber, then, was to do what Jomini and Moynier initially thought impossible: to lay down “maxims” for the conduct of civil war by applying international law, thereby bringing civil war within the pale of civility.


Abraham Lincoln’s decision to pronounce the conflict in the United States “a great civil war” was, as suggested, contestable even in 1863. For to do so was to presume the Union’s interpretation of the Confederacy’s actions. It was to affirm that combatants on both sides had been, and still remained, members of the same political community: the United States of America. The label also highlighted what was at stake in the conflict: the unity of the nation and the inviolability of the Constitution, as well as the illegitimacy of unilateral secession. To term it “the Civil War” at any time after 1865 has been to accept the victory of that interpretation and of the principles the Union had sought to protect and defend. That conclusion was hard-won, and still the term would remain a source of friction well into the twentieth century. But it would prove futile to seek to change the accepted name for the defining cataclysm of American history. It would also become morally unacceptable to challenge the logic of the term “Civil War,” implying as it did unity as much as division and, as so often in the history of ideas of civil war, recognition of commonality amid rupture. This paradox would remain especially acute in the North American case as the conflict became the test case for the legitimacy of secessionist civil war everywhere.

For supporters of the Confederacy, it was not a war between fellow citizens or members of the same “Civil Society,” as Algernon Sidney might have said. It was a secessionist civil war, fought to establish among other things the right to secede and ignited by a series of acts of secession from the Union. This made it, from the Confederate vantage point, not an intra-national conflict but an international one, a war between polities, not within the bounds of a single community. The Confederate states argued that they had exercised their constitutional right to secede from the Union and believed they had now formed a new union, the Confederate States of America, which was entitled to conduct its own affairs, including its own military defense, as an independent entity. By contrast, the logic of the Union, and of Lincoln, rendered the Confederacy’s secession an act of “rebellion” and the conflict to suppress it a “civil war,” and yet Lincoln himself used the term “rebellion” almost six times as often as “civil war” during the conflict.13 The larger historical context may suggest why.

The import of the term “civil war” was under particular pressure in the middle of the nineteenth century. This was a period of thickening global connections, which rendered the ancient boundedness implied by “civil” war moot. Eighteen months before the Gettysburg Address, the French novelist Victor Hugo (1802–85) had a central character in his masterpiece Les Misérables (1862) contemplate the changing implications of civil war in a cosmopolitan world. (Hugo was a great admirer of Lincoln’s; after his assassination in 1865, the French author helped to organize a subscription for a commemorative medal to be sent to Mary Todd Lincoln in honor of the greatest victim of a great civil war.)14 Les Misérables got around rapidly in English translation in New York in 1862 and then the following year in Richmond, Virginia, as “almost the only fresh literary food of those engaged in a slaveholders’ rebellion,” in the dismissive assessment of a Rhode Island newspaper.15

Hundreds of pages into Hugo’s masterpiece, Lincoln’s contemporaries could have read the reflections on civil war of Marius Pontmercy, son of a noble veteran of Waterloo. (That the name Marius recalls Sulla’s adversary in Rome’s first civil war could hardly have been accidental.) As Marius heads toward the barricades in Paris to battle against the restored Bourbon monarchy, he knew “he was to wage war in his turn and to enter on the field of battle, and that that field of battle which he was about to enter, was the street, and that war which he was about to wage, was civil war!” He shudders at the thought, wondering what his heroic father might have made of his actions, even as he expresses some philosophical doubt about the very category:

Civil war? What does this mean? Is there any foreign war? Is not every war between men, war between brothers? War is modified only by its aim. There is neither foreign war, nor civil war; there is only unjust war and just war…War becomes shame, the sword becomes a dagger, only when it assassinates right, progress, reason, civilization, truth. Then, civil war or foreign war, it is iniquitous; its name is crime.16

The action of the novel at this point is set in 1832, but Pontmercy’s musings reflect Hugo’s own apprehensions of the blurred boundaries between civil war and other kinds of conflicts. Within the broader setting of “the whole great family of man” (to take a pointed phrase from Lincoln), any distinctions between civil war and foreign war had begun to collapse.17

The U.S. Civil War took place at the heart of a global capitalist economy built on cotton and the labor of the enslaved, with ramifications felt in the Caribbean, Europe, Egypt, and South Asia.18 It also occurred amid a global explosion of violence in the mid-nineteenth century. This period began with what were, in proportion to population, the century’s two bloodiest wars—the Taiping Rebellion in China (1850–64) and the War of the Pacific (1879–84), which saw Peru and Bolivia aligned against Chile; it also included the Crimean War (1853–56), the Indian Rebellion or “Mutiny” of 1857, Mexico’s Reform War (1858–61), Japan’s Boshin War (1868–69), the Franco-Prussian War (1870–71), and Spain’s successionist Third Carlist War (1872–76).19 For the Americas, the interval marked the last among a great run of upheavals since the mid-eighteenth century, during which efforts at imperial reconstruction had led to independence movements, revolutions, and civil wars, often with the result, if not always the original aim, of making smaller states out of larger ones and empires.20

Nor was the violence of the Civil War an exceptional response to the circumstances. From the Dutch Revolt of the 1580s to the American Revolution, and from the United States in 1861 to Yugoslavia in 1991, secession has routinely led to civil war. A group within a state, exasperated by what it sees as the suppression of its right to self-determination, asserts that right as a claim to independent statehood. In response, the existing state asserts its right to territorial integrity and authority over all its inhabitants, resisting the group’s claim with coercive violence. Secession—the attempt to create a new state—thereby leads to civil war: armed conflict within an established state. To be sure, there have been some peaceful secessions—for example, Norway’s from Sweden in 1905, Iceland’s from Denmark in 1944, Singapore’s from the Malaysian Federation in 1965, Montenegro’s from Serbia in 2006, and Kosovo’s, also from Serbia, in 2008—but these have been the exceptions.21

The logic of history seemed as impeccable as it was implacable: secession causes civil war, just as civil war was until recently the most likely outcome of attempted secession. The most comprehensive recent tally of warfare around the world counts 484 separate wars between 1816 and 2001; 296 of those were typed as “civil” wars, of which 109 were fought to create a new state rather than take control of an existing one. Secessionist conflicts thus constituted more than a fifth of all wars in the past two centuries accounting for a substantial portion of the civil wars in that period. They tended to occur most often “during the two institutional transformations that have shaped the landscape of the modern world”—that is, imperial expansion and the process of state creation, especially after decolonization. Furthermore, the likely onset of such wars “show[s] a dramatic peak immediately before nation-state formation,” while “the odds of civil war onset are more than five times higher in the first two years after independence than in the other post-independence years.”22 In this longue durée perspective, the American Revolution looks typical and the U.S. Civil War anomalous, again if only for its belatedness, not for its violence.


The global violence of the Civil War era raised a question that would be faced repeatedly in the nineteenth and twentieth centuries, with consequences down to our own time: Was it possible to civilize civil war? Nothing could soften its trauma, of course: the sundering of the political community, antagonism within families, the death to kinship, the fear of recurrence, the shame of both victory and defeat. But while perpetual peace was an ever-receding hope, there was some evidence war could be tamed if not abolished. Since the seventeenth century, European powers and their heirs in the Americas had striven to regulate the conduct of their conflicts, bringing them under the rule of law. Alas, the treatment of non-European peoples became quite another matter; a toxic by-product of this effort was an opening gap between those who were to be dealt with humanely and those who were not, the latter not even considered human. The difference corresponded to the line being drawn between civility and incivility, between the realm of civilization and the barbarism that lay outside.

As far as the law was concerned, civil war was one thing; wars between states quite another. So long as states were left to police actions within their own borders, it would be up to their discretion to decide whether to treat rebels as criminals rather than as belligerents. The horrors of warfare on the battlefields of mid-nineteeth-century Europe did lead to the most famous humanitarian response to the inhumanity of war, the foundation of the Red Cross in 1863, but even this institution originally excluded civil wars from its remit. At only the second meeting to discuss creating an organization to aid the wounded, the founding committee moved that “no action should be contemplated during civil wars,” though it reserved the right to extend its operations in the future.23 In similar fashion, the original Geneva Convention of 1864 did not explicitly extend its protections to combatants in civil wars, though within a decade the founders of the Red Cross and framers of the Convention would have second thoughts on the matter.24

Until that change of heart, the question remained of how civil war could be brought within the emergent global framework of law. One possible answer had come on the eve of the U.S. Civil War from the English liberal philosopher John Stuart Mill (1806–73). Mill used the case of intervention in civil wars to illuminate the new geography of civilization and barbarism; during the conflict itself, he would redraw the frontiers of barbarism to include the Confederacy. In “A Few Words on Non-intervention” (1859), he mapped Great Britain’s ethical responsibilities in an unstable world divided between self-preserving sovereign states, “members of an equal community of nations, like Christian Europe,” and “parties…of a very low grade of social improvement”—that is, peoples potentially subject to empire. The advance of European empires across the globe had grown only more urgent since a century earlier, when Vattel had addressed “the disputed question…whether a nation is justified in taking part, on either side, in the civil wars or party contests of another: and chiefly, whether it may justifiably aid the people of another country in struggling for liberty.” Mill argued for two grounds on which it would be legitimate for outside powers to intervene: if the aim was to help a people throw off a foreign ruler rather than a native government, and when there is “a protracted civil war, in which the contending parties are so equally balanced that there is no probability of a speedy issue” and outside force is needed to end the conflict.25

These conditions drastically restricted the possibilities for intervention imagined by Vattel, but Mill thought them compatible both with contemporary practice and with international morality. On this basis, Mill vehemently supported British neutrality in the American Civil War and equally strongly opposed any concession to the Confederacy, a “Power professing the principles of Attila and Genghis Khan as the foundation of its Constitution.” Peace, then, was not the answer, but rather “war to protect other human beings against tyrannical injustice; a war to give victory, to their own ideas of right and good, and which is their own war, carried on for an honest purpose by their free choice—[this] is often the means of their regeneration.” While his thinking could not justify intervention, Mill nonetheless saw the war as a crusade for four million enslaved persons who had not consented to secession but were “human beings, entitled to human rights.”26

As Mill was well aware, the modern international order rests on two fundamental but incompatible principles. The first is sovereign inviolability or independence. Within its own borders, each state has primary authority and jurisdiction, with which no outside power may interfere. The second is the idea that human rights must be respected and the international community has the power to intervene on behalf of those who seek to exercise their rights or find them to be violated. The two principles are enunciated in the 1945 charter of the United Nations, but they both have much deeper roots. In fact, Vattel might have been the first to articulate them together, in his repeated axiom that states—though his term, in French, was “nations”—are “free and independent.”27 These words would find their way without acknowledgment into the U.S. Declaration of Independence, which announced that the former colonies were now “Free and Independent States” while also affirming the natural equality of human beings and their rights of resistance. The early stages of the conflict in North America would show that these two foundational principles could be detached from each other and that each alone could be the spark for civil war.

One of the few observable regularities in world history since 1776 is that any state that has declared its independence will resist attempts by any section of its population or territory to become independent in turn. That is so notwithstanding the would-be secessionists invoking the same principles, even in the same language, that informed the original Declaration of Independence. Thus, for example, in December 1860, South Carolina’s secession convention approved a declaration that said in part,

South Carolina has resumed her position among the nations of the world, as a separate and independent State; with full power to levy war, conclude peace, contract alliances, establish commerce, and to do all the other acts and things which independent States may of right do.28

(The South Carolina declaration, like those of other Confederate states, studiously avoided any mention of human equality and the rights of all human beings, focusing on the rights of states.)

To the nation that had begun with its own Declaration of Independence, the only response to this challenge could be military action: war. In his address to Congress on July 4, 1861, Lincoln argued that the Confederate attack on Fort Sumter three months earlier had starkly presented not just to the United States but “to the whole great family of man the question, whether a constitutional republic, or a democracy—a government of the people, by the same people—can or cannot maintain its territorial integrity against its own domestic foes.” By their preemptive strike, the Confederates themselves had made the choice one of “ ‘Immediate dissolution, or blood.’ ” Yet Lincoln rejected his enemies’ description of their action as secession; he mocked “the seceded States, so called,” and rebuffed their “position that secession is consistent with the Constitution—is lawful and peaceful”—by means of a reductio ad absurdum. If it were agreed that secession was constitutional, he reasoned on, then logically the Confederate states should retain a right of secession in their own constitution, even at the cost of self-destruction: “The principle [of secession] itself is one of disintegration, and upon which no government can possibly endure.”29

Lincoln implied that in the American case secession and civil war were joined both sequentially and causally—sequentially because the “so called” secession of South Carolina and the other states of the Confederacy had required the Union to defend its integrity; because the armed response took place within the borders of the United States, it led to a domestic, or civil, war. And they were linked causally because without the assertion of a right to secede, there would have been no need for formal hostilities: no secession, no civil war. For Lincoln, these connections were hardly accidentally or exclusively American. These inevitabilities could, he thought, be felt by “any nation,” any member of “the whole great family of man,” whose statehood was grounded in its territorial integrity. With the benefit of a further 150 years’ experience, which has seen the global proliferation of states, we inevitably hear Lincoln not just as the great emancipator and champion of popular government but also as the defender of indivisible sovereign statehood itself.

Lincoln acknowledged that the very term “secession” was almost as incompatible with a constitutional order as the act itself. In 1861, he would insist to Congress that the withdrawal of the Confederate states from the Union was in fact not a secession but a rebellion. This was Lincoln’s own view, but he argued that the distinction was not his alone: “It might seem, at first thought, to be of little difference whether the present movement at the South be called ‘secession’ or ‘rebellion.’ The movers, however, well understood the difference. At the beginning, they knew they could never raise their treason to any respectable magnitude by any name which implies violation of law.” Accordingly, he went on, the Confederates had “sugar-coated” rebellion with the argument that secession was compatible with the Constitution and thereby succeeded in “drugging the public mind of their section for more than thirty years.”30

Lincoln recognized that secession could be legal only if it was consensual; otherwise “no State, upon its own mere motion, can lawfully get out of the Union…resolves and ordinances to that effect are legally void; and…acts of violence within any State or States, against the authority of the United States, are insurrectionary or revolutionary, according to circumstances.”31 He was apparently untroubled by what is now the most pressing question in contemporary legal discussions of secession—that is, whether or not international law acknowledges a norm in favor of the practice.32He implicitly assumed that it did not and asserted instead the proposition that it was incompatible with current American constitutionalism. As he argued in the Gettysburg Address, the basis of that constitutional order was the principle “that government of the people, by the people, for the people, shall not perish from the earth.” That principle had to be defended, even at the cost of a great civil war to coerce the breakaway states back into the Union.33


Within a few weeks of the bombardment of Fort Sumter, all sides—Northern and Southern, American and foreign—had recognized the existence of a war within the borders of the United States.34 But the question of just what kind of conflict it was, and hence what rules should apply to its conduct, remained controversial. In the eyes of supporters of the Confederacy, President Lincoln had prejudged the issue when in April 1861 he had ordered ports from Chesapeake Bay to the mouth of the Rio Grande to be blockaded on the grounds that the states of the Confederacy had raised “an insurrection against the Government of the United States.” This meant, among other things, that Union forces could capture neutral ships attempting to supply the Confederate states on the grounds they were illegally supplying an enemy in time of war.35

In February 1863, the Supreme Court heard four cases, collectively known as the Prize Cases, on appeal from courts in Boston, New York, and Key West. The plaintiffs argued that the blockade, and the subsequent use of prize law to distribute the proceeds from four captured ships, applied the laws of war where no war had been declared, and hence such laws could not operate. The main question before the Court was, therefore, whether a state of war existed that would justify the president’s invocation of the laws of war. Justice Robert Grier, writing for the majority in March 1863, was persuaded by the government’s lawyers that a war was indeed in progress. To call the action of the Confederacy an “insurrection” did not preclude that fact, nor could the absence of a declaration of war prevent the government from treating its adversaries as belligerents: “A civil war always begins by insurrection against the lawful authority of the Government. A civil war is never solemnly declared; it becomes such by its accidents—the number, power, and organization of the persons who originate and carry it on.” The president was bound to face this conflict “in the shape it presented itself, without waiting for Congress to baptize it with a name,” but Grier himself did not hesitate to call it the “greatest of civil wars.”36

Vattel’s epoch-making definition of civil war lay behind Grier’s judgment, even though he did not follow Vattel’s analysis of the consequences of that description. Vattel had offered a factual description of when a civil war had broken out and of what would allow all sides to recognize that two warring nations had emerged within the same territory. The existence of a war would be clear to all: by the “number, power, and organization” of those who prosecuted it. It needed no declaration, but once it was evident as war between two nations, domestic law no longer applied. Rather, the law of nations, including the laws of war, was operative.37

The U.S. Army officer Henry Halleck attacked Vattel’s account of civil war at length in his International Law (1861) early in the course of the hostilities. His arguments were hardly abstract; they could be said not only to apply to the situation at hand but even to arise directly from it. While agreeing with Vattel that the two parties in a civil war are entitled to treat each other according to the laws of war, Halleck rejected the claim that foreign powers may regard both as independent states and assist whichever they decided had the just cause: “Such conduct would be a direct violation of the rights of sovereignty and independence.” He no doubt had the American Revolution in mind when he went on to say that foreign states may recognize “the independence and sovereignty of a revolted province…when that independence is established in fact,” even before the former sovereign has acknowledged it. (On these grounds, France and other powers had entered into diplomatic and military relations with the United States long before Great Britain had formally recognized American independence by the Treaty of Paris in 1783.) Yet he strongly condemned Vattel’s view that “a foreign state may take part in the civil wars of its neighbors.” This was a charter for international chaos, because “there would be no limits to its right to interfere in their domestic affairs.”38

In this dispute, as so often, much depended on what was meant by civil war. Halleck offered his own factual and historical definition later in his work. He distinguished civil wars from what he called (following Jomini) “wars of opinion”—whether these were “political wars,” such as the wars of the French Revolution, or religious conflicts, like the Crusades or “the wars of Islamism”—and from national wars of liberation or revolt against oppression.39 His first definition was narrowly successionist—that is, confined to those wars, whether monarchical or republican, “which result from hostile operations, carried on by different parts of the same state, as the wars of the roses in England, of the [Catholic] league in France, of the Guelphs and Ghibellines in Italy, and of the factions in Mexico and South America.” Civil wars, he continued, could also include “wars of insurrection and revolution,” when they involve different factions fighting for ascendancy or a change of government—that is, what I have earlier called supersessionist civil wars. However, “mere rebellions…are considered as exceptions to this rule, as every government treats those who rebel against its authority according to its own municipal laws.” To accord every rebel group the full panoply of protections guaranteed by international law to legitimate sovereigns “would be both unjust and insulting to the government of the state against which the rebellion or revolution is attempted.”40 According to Halleck, then, rebellion and civil war were quite different beasts. The question in 1861, as in 1863 and later, was whether a rebellion or a civil war was taking place within the territory of the United States.

This collision of perspectives was a problem not only for politicians but even more acutely for military commanders, especially on the Union side. Under what rules of engagement would the Union army treat the rebels? Did the laws of war apply, and would bringing them to bear imply that the conflict was, indeed, one between the forces of separate states? Could such an irregular form of conflict be constrained by any rules of combat? If one side saw the other as rebels or insurgents, could there be any limits on their behavior toward such outlaws? And why might it matter if this was not an international war but a civil war? Another of Lincoln’s advisers, the Maryland anti-secessionist and pamphleteer Anna Ella Carroll (1815–94), answered such questions defiantly in 1861 with support from Vattel: “This is a civil war; and, therefore, the Government may employ all the Constitutional powers at its command for the subjugation of the insurrectionary forces in the field. But while it is enabled to employ all the powers, it is obliged to observe at the same time, all the established usages of war. For the same enlightened maxims of prudence and humanity are as obviously applicable to a civil war as to any other.”41

The Supreme Court’s decision in the Prize Cases—deeply divided though it was at 5–4—opened the way for legally defining the difference between civil war and kindred concepts like rebellion and insurrection, as well as applying “the usages of war” to the present situation. What followed would in fact be the first-ever attempt to define civil war, in response to centuries of contestation and confusion. By no coincidence, the instigator of the search for a lawyer’s definition had been Halleck, an international lawyer as well as an army general. The person he recruited for this delicate task was Francis Lieber, the lawyer who had probably thought longer and harder about the legal significance of civil war than anyone at the time. Alas, even he would find the responsibility almost too great, and the result was only more perplexity.

Lieber had fought at the Battle of Waterloo (where he was left for dead on the battlefield) and, after immigrating to the United States, later became the first American professor of political science. Having begun his career teaching at the University of South Carolina, he was increasingly appalled by the institution of slavery, not least at his own college, and in 1857 he moved to New York, where he taught law and politics at Columbia College (now Columbia University).42 Lieber’s main claim to fame would be his authorship of the General Orders No. 100 of the Union army in 1863. Better known as the Lieber Code, it remains famous as the first attempt to codify the laws of war, and therefore as the direct ancestor of the Geneva and Hague Conventions and the foundation of the modern laws of war.43 Lieber’s qualifications to create it were more than academic. As well as having experience of living on both sides of the sectional divide, between North and South, he knew the division even more personally. Three of his sons were in uniform, two fighting for the Union and one for the Confederacy. “Behold in me the symbol of civil war,” he lamented in May 1861.44

Lieber had been reflecting on the issues of rebellion, revolution, and, crucially, civil war for many years before drafting his Code, but under the pressure of the job he was forced to change his mind on his definitions. In some early notes from around 1850, he ran through the various terms that could be used to describe different species and degrees of revolution—“Rising,” “Revolt,” “Riot,” “Insurrection,” “Sedition,” “Rebellion,” and so on—and included among them both “Secession” and “Civil War.”45 Around the same time, he reflected at length on the question of secession, especially in relation to South Carolina, where he was then living and teaching. He viewed the prospects of a successful secession dimly: “No peacible secession is possible…theory or no theory, right or no right, the Union will say: We must keep you; we cannot afford one of the south to cave in; the Union shall continue.”46 And so, of course, it would transpire a decade later. Success, or the prospect of success, was for him a major criterion for distinguishing the different kinds of collective antistate actions: “A State can resist, can rebel and if the rebellion be successful it will be called revolution. But…[l]et us call things by their right names. The right of secession is one thing and that of rebellion another.” His example of a successful “rebellion” in this case was the American Revolution, in which “the Declaration of Independence gave…a national existence” to what, until July 4, 1776, had been British colonies.47

Early in the war between the North and the South, Lieber had again grappled with the definition of civil war. Only a few months after the hostilities began, between October 1861 and February 1862, he gave a series of lectures to his Columbia College students titled “Laws and Usages of War.” He began by noting that he and his listeners were living in the “most martial period of our race” and, more specifically, that they were “in the midst of a bitter civil war in this country, while all Europe is preparing for war on a gigantic scale…We live in a grave age.” He alluded to other conflicts, including the Crimean War and the Taiping Rebellion, and showed that he was well aware that the mid-nineteenth century was a moment of peculiar global instability. “Rebellion in China and here” made the relevance of the laws of war to civil war especially urgent but hardly clear. He followed thinkers like Rousseau in defining war as a contention between “political societies,” not among individuals; only formal combatants could be accounted enemies. This led him to a distinction between “war” and civil war, the closest he would come to hazarding a definition of the latter before his work on the Code: “In international law we mean, as a matter of course, by war the contest between nations or independent governments, acknowledged as such by the family of nations. By civil war we mean the protracted state of active hostility of one portion of a political society against another portion.”48

Lieber argued that the laws of war applied in civil war as in “true war or contentio justa [just conflict]” (a notable distinction) but only while also recognizing the continuing force of domestic law over those opposing the legitimate government:

But there is this difficulty shrouding all civil war, that on the one hand the rebel or insurgent is besides being a warfarer, a belligerent, a criminal, that is to be punished or at any rate punishable by the lawful government, and that on the other hand the large number of the insurgents (without which they would not have entered the civil war) precludes the lawful punishment and leads to those amnesties which are proclaimed while the criminality of the rebel may indeed be the greater.

At this point, Lieber did not distinguish as clearly as Halleck would in his International Law between rebellion and civil war. A civil war could have the features of both a “true war or contentio justa” and a domestic police action against insurrection, but not all insurgents could be punished as if they were common criminals: “It is a question of expediency, and not of law or morality.”49 How to overcome this double nature of civil war—as the conduct of both true war and mere criminality—presented a dilemma that Lieber could not resolve. His lecture notes include a fragment reflecting on the various principles underpinning the laws of war as the prelude to an account of their application in civil war. They tail off inconclusively: “Now in Civil War &c &c.” Likewise, when, later in 1862, Lieber would publish a pathbreaking short treatise titled Guerrilla Parties: Considered with Reference to the Laws and Usages of War, he would deliberately not “enter upon a consideration of their application to the civil war in which we are engaged.”50

That would have to wait until Henry Halleck invited him, in August 1862, to present his views to the public “on the usages and customs of war.” Halleck’s request came at a poignant moment. In his reply to the general’s request, Lieber revealed that he had just received news of his son Oscar’s death in Richmond, Virginia, after fighting in the Confederate army at the Battle of Williamsburg. “Civil war,” he said mournfully, “has thus knocked loudly at our own door.”51 He soon began work on a short text on the laws of war, which he had been contemplating for some time—his Columbia College lectures were probably a preparation—but which now gained added impetus from Halleck’s invitation and the tragedy hanging over his family. The problem, he confided to the U.S. attorney general, Edward Bates, was the lack of authoritative precedents in the legal literature. “Civil war has been little treated by the authors on the Law of War. Nor has there ever been a Civil War with the peculiar characteristics which signalize ours.” He would, he told Bates, have to rely instead on “the authority of common sense.”52

The correspondence between Halleck and Lieber revealed just how little guidance common sense could offer at such a fraught moment. Lieber’s draft had deliberately not distinguished among civil war, rebellion, insurrection, and invasion, but Halleck asked for each to be delineated in the Code. The war was not quite into its second year when Lieber circulated what he thought was a complete draft of the Code in February 1863. A handful of copies had been printed to allow a select group of readers to annotate and comment on Lieber’s work. On one remaining copy, Henry Halleck notes a striking absence from the list of the laws of war: “To be more useful at the present time it should embrace civil war as well as war between states or distinct sovereignties.”53 Lieber might have deliberately omitted civil war in an effort to dodge difficulties he could already perceive it would create. Yet, ever the keen lawyer, after Halleck’s nudge, he did intend to offer his political masters in Washington, D.C., a precise definition. But it was easier said than done. “I am writing my 4 sections on civil war and ‘invasion,’ ” Lieber wrote to Halleck in March 1863. “Ticklish work, that!”54

The account of civil war Lieber had provided to his students in New York—“the protracted state of active hostility of one portion of a political society against another portion”—was too inexact for the formal purpose of codification, particularly this one. After all, the paragraphs on civil war and its analogues would be the culmination of the Code, the final set of distinctions its readers in the Union army would take away with them. How, then, did Lieber define civil war? He distinguished it both from “insurrection” and from “rebellion,” in ways that reflected the specific political conditions under which he wrote in the spring of 1863:

149. Insurrection is the rising of people in arms against their government, or a portion of it, or against one or more of its laws, or against an officer or officers of the government. It may be confined to mere armed resistance, or it may have greater ends in view.

150. Civil war is war between two or more portions of a country or state, each contending for the mastery of the whole, and each claiming to be the legitimate government. The term is also sometimes applied to war of rebellion, when the rebellious provinces or portions of the state are contiguous to those containing the seat of government.

151. The term rebellion is applied to an insurrection of large extent, and is usually a war between the legitimate government of a country and portions or provinces of the same who seek to throw off their allegiance to it and set up a government of their own.55

The context since 1861 had clearly shaped Lieber’s distinctions. The difference between “insurrection” and “rebellion” was one of degree, with the latter approaching the condition of interstate conflict, or war, if undertaken for “greater ends,” such as throwing off allegiance and setting up an independent government—that is, a self-styled secessionist movement such as the Confederacy.56

Lieber presented two distinct definitions of civil war, one traditional and one novel. The first—“war between two or more portions of a country or state, each contending for mastery of the whole”—could be traced back to the Roman tradition and corresponds to what I have called a “supersessionist” model. The second conception—“sometimes applied to war of rebellion, when the rebellious provinces or portions of the state are contiguous to those containing the seat of government”—was unprecedented, both legally and historically. Lieber had made it up out of whole cloth, tailoring it to the needs of the moment. The U.S. Civil War might have been fought between two portions of the country, but only the Union aimed at recovering overall mastery or claimed to be the legitimate government over the whole territory. The Confederate states professed some moral continuity with the original rebellious colonies of the American Revolution, but that amounted to no claim on the territory of the states remaining in the Union. And yet, in Lieber’s construction, the boundary between rebellion and civil war collapsed; the one (“war of rebellion”) could be redescribed as the other (“sometimes applied…”) when the circumstances were right—that is, when the “rebellious provinces” abutted “the seat of government,” as, of course, they did in North America in 1863, with the U.S. capital of Washington, D.C., placed within the state of Virginia.

By Lieber’s second definition, the Civil War was therefore not a civil war at all; it was in fact a rebellion. This validated the Union’s response, because the U.S. Constitution provided for the means to “suppress Insurrections,” including the suspension of habeas corpus “in Cases of Rebellion,” which Lincoln had done (with Lieber’s advice and support) in 1861. After the war, the Fourteenth Amendment to the Constitution (1868) would refer accordingly to “engage[ment] in insurrection or rebellion” as a disqualification for public office.57 And, as we have seen, the official history of the conflict would be titled The War of the Rebellion, to drive home the Unionist account of the war as an uprising against a legitimate government.58 In public and in private, however, both Lieber and Lincoln referred to it variously, usually as a “rebellion,” sometimes as a “civil war,” making a mockery of the lawyer’s fretful efforts at precision in distinguishing them.

Lieber’s definition nonetheless had an afterlife. As the Code’s leading historian has written, “The document was instantly influential” after Lieber had sent copies to Europe, with translations and imitations appearing across the continent from the Netherlands to Russia between 1866 and 1896.59Two years after the Italians had adopted a parallel code, General Orders No. 100 was reissued verbatim by the United States in 1898, this time in the context not of a civil war but of an “insurrection” in the Philippines.60 Lieber’s Code would still be studied by the U.S. Army in the aftermath of the terrorist attacks of September 2001; it was reprinted in 2007 as part of a study of a “masterpiece of counterguerrilla warfare” in the archipelago in 1901–2.61 Since the Code’s first appearance, U.S. Army field manuals had made no attempt to revise Lieber’s definition of civil war, only updating the rubric somewhat after the Geneva Conventions of 1949 to cover “armed conflicts not of an international character.”62

In the intervening years, the naming of the most divisive war in American history continued to be controversial. During the conflict, there could be no agreement on what to call it. Although in its early stages even Southerners referred to it as a civil war, they generally came to prefer other terms: “the war,” “the War for Independence,” and even “the Revolution,” to suggest continuity with an earlier struggle for self-determination led by white slaveholders from the South such as George Washington and Thomas Jefferson.63 Northerners meanwhile called it “the Rebellion,” “the War of Secession,” and “the Civil War.” It was only after the end of formal hostilities that other names proliferated—“the Late War,” and “the Late Unpleasantness,” for instance. (One assiduous collector has discovered 120 different terms.) “The War Between the States” was mostly a postwar designation, and it gained special prominence in 1899 when the United Daughters of the Confederacy approved a resolution that it replace all references to the Civil War, the War of Secession, and the War of Rebellion. As one implacable Confederate woman argued, “Don’t allow the War of the States to be called a Civil War. If we allow this, we own that we were one State, not many, as contended.”64

It was not until 1907, while debating a bill to provide pensions for veterans of the Mexican War and the Civil War, that the U.S. Congress agreed that the official name would be the “Civil War.” A Democratic senator had protested that it had been a “War of Secession”: “It was a war to establish the right of secession…The war was in the nature of a rebellion, and to a certain extent it was a civil war, but in the broad sense, in the full sense, it was a war of secession.” A Mississippi senator likewise protested, “It was not a civil war and it was not a war of rebellion. It was a war between sovereign States.”65 But these protests, like those of other sympathizers of the Lost Cause, were in vain. “No more is to be heard of the ‘war of the rebellion’ nor the ‘war between the States,’ ” a Washington, D.C., newspaper reported the morning after the debate. “What Gen. Butler once called in derision ‘the late unpleasantness’ is henceforth to be known as ‘the civil war.’ The Senate so decided yesterday.”66 The United Daughters of the Confederacy was undeterred and continued to campaign for changes to school textbooks and to press Congress for recognition of “the War Between the States,” on the grounds that “ ‘Civil War’ is defined by the best authorities as a war between the citizens of a ‘common country,’ ‘citizens of the same nation,’ etc. Now for four years we maintained an entirely separate government from that of the United States, being an entity known the world over as the Confederate States.”67 These efforts were a relatively minor part of the enduring battle over the memory of the Civil War and had strikingly little relevance to the African American population of the United States. For them, the war had been the motor of emancipation—“the Abolition War,” in Frederick Douglass’s phrase—the origin of both profound hope and equally deep disappointment, yet still a great good, perhaps even a gift from heaven.68


During the U.S. Civil War—as a conciliatory consensus now agrees to call the conflict in the United States—the category of civil war came firmly under the authority of lawyers for the first time. Beginning with Francis Lieber, they were the first professional group to claim competency to define the undefinable and its precise determinants and empirical benchmarks. Vattel and Halleck had led the way in attempting to describe civil war in the context of the law of nations (or what, by Halleck’s time, had become known as international law). But Lieber was the first to try to discriminate civil war from its near neighbors “insurrection” and “rebellion,” however arduously, as he complained, and with limited success, as we have seen. The meanings of civil war would continue to grow, the urge to restrain the proliferation eventually peaking during the latter years of the Cold War. But it originated a century earlier, finding its agent in a man who almost perished at Waterloo. That history of European battlefields haunted Lieber as much as the personal and national tragedy of the war of 1861–65.

Another history would continue to haunt memories of the U.S. Civil War, both in the short and in the long terms: the history of Rome. Liberated from the Roman narratives about the natural recurrence of civil war, supporters of both the Union and the Confederacy nonetheless reached back to the ancients for analogues of their struggle and its aftermath. The novelist and poet Herman Melville (1819–91), for one, affirmed the importance of the Roman past even in the act of repudiating it in the poem he wrote to commemorate the surrender at Appomattox on Palm Sunday, April 9, 1865:

The warring eagles fold the wing,

But not in Cæsar’s sway;

Not Rome o’ercome by Roman arms we sing,

As on Pharsalia’s day.

But Treason thrown, though a giant grown,

And Freedom’s larger play.

All human tribes glad token see

In the close of the wars of Grant and Lee.69

With its allusions to Caesar, Pompey, and Lucan, Melville’s lines are almost an epitaph to the Roman conception of civil war in the era of industrialized slaughter.

Almost, but not quite: in June 1914, the United Daughters of the Confederacy unveiled a monument to the Confederate dead at Arlington National Cemetery outside Washington, D.C., that carried on with the Roman tradition. On the plinth is the seal of the Confederate States of America with the motto “To Our Dead Heroes by the United Daughters of the Confederacy Victrix Causa Diis Placuit Sed Victa Catoni” (“the conquering cause pleased the gods, but the conquered [pleased] Cato”).70 The line is from the first book of Lucan’s Civil War, and the ambivalence was Lucan’s own. It implies that a civil war could not be just on both sides but that there could still be moral consolations, however illusory, even for the defeated. Friedrich Engels had said as much to Karl Marx in a letter of May 1862: the Confederates, he thought, “abide by the outcome of the big battles and console themselves with victrix causa diis, etc.”71 What Lincoln had called “a great civil war” at one cemetery in Pennsylvania was transmuted by the Roman allusion into an emblem of the Lost Cause at another American burial ground. As so often, progress toward perpetual peace entailed a march through the graveyards filled by civil wars.

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