Occupation Resistance, War-Rebels, and the Lieber Code

by | Dec 3, 2021


The origin of the codified law of belligerent occupation is often traced to the Hague Regulations of 1899 (updated in 1907). However, the Lieber Code of 1863 laid important and underappreciated legal groundwork for the Hague treaties’ occupation provisions. In it, Professor Francis Lieber tackled legal and operational dilemmas that continue to vex occupying powers and captured principles still evident in the law today.

Lieber’s Sources

Lacking the benefit of multilateral treaties or extensively recorded custom, Lieber looked to early legal publicists to inform his Code. The work of the Enlightenment diplomat Emer Vattel[1] and the natural law theoretician Hugo Grotius[2] are evident in the Code. Lieber also drew on his personal experience as a combat soldier and his own insights into the necessities of combat during the American Civil War.

Ample authority for Lieber’s core provisions of the law of belligerent occupation are found in the venerated works of Vattel and Grotius, although their works did not necessarily reflect reports of settled law and practice. They were more often aspirational or admonitory.

Vattel had hoped that a “generous conqueror will study to relieve his new subjects, and mitigate their condition; he will think it his indispensable duty. ‘Conquest [quoting Montesquieu] ever leaves behind it an immense debt, the discharge of which is absolutely necessary to acquit the conqueror, in the eye of humanity.’” Vattel pointed out that the generosity of the occupier would not only to serve humanitarian purposes, but would also serve its own political purposes. He stated, “what fidelity, what assistance, can you expect from an oppressed people?”

Grotius earlier expressed very much the same idea. He cautioned that territory may be “gained by Force, but must be retained by Justice,” and that it was wise not to molest inoffensive citizens (e.g., women, children, priests, old men, scholars, farmers, merchants, mechanics) and to refrain from destroying public and sacred buildings and articles. A light hand in occupation would serve both humanity and kingship: “that their own Sovereignty should be left to the Vanquished is not only agreeable to Humanity but often also to Policy.”

Lieber’s Conclusions

At least 40 of the Lieber Code’s 157 articles deal directly or indirectly with belligerent occupation. Broad subjects include the treatment of civilians, enemy property, and the laws of the displaced power.

Inoffensive Persons[3]

Unlike the practice in ancient times, Lieber insisted that civilians were not to be murdered, enslaved, forced into the conquering army, or carried off. He maintained, “Protection of the inoffensive citizen of the hostile country is the rule.” He acknowledged that the civilian population would inevitably suffer hardships in war. But he insisted that “the unarmed citizen is to be spared in person, property, and honor as much as the exigencies of war will admit.”

Still, Lieber differentiated civilians according to loyalty. In the context of the Civil War, he concluded that Union sympathizers and secessionists could be treated differently. He stated the occupying force must “protect the manifestly loyal citizens” and was permitted to “throw the burden of the war … on the disloyal citizens.”

Public and Private Property

While Lieber envisioned a permissive regime with respect to enemy property, he identified important limits on the occupying power. He concluded the occupier may take enemy public property for government or army purposes. But he indicated that title did not transfer. Title to property taken for army use was only provisional — i.e., for the duration of the occupation.

Private property, on the other hand, could not be seized under the Code except if required by reason of military necessity, and then only for the army or the government, not for personal use. Additionally, soldiers could not use their positions in the occupation for private gain. As understood by Lieber, no private violence was allowed against either the person or property of the occupied civilian population. Robbery, rape, pillage, looting, killing, maiming, and arson by individuals were all clearly prohibited.

Cultural Objects[4]

His Code included important protections for cultural objects as well. Property belonging to a church, hospital, school, museum, and other charitable or scientific establishment was immune from the general rule that public property could be taken for use by the occupant. He went further and identified an affirmative obligation to protect classical works of art, libraries, scientific instruments, and hospitals, which “must be secured against all avoidable injury,” even during a bombardment.

Local Law and Civil Society[5]

Addressing governance, Lieber opened by emphasizing the occupant’s duties with respect to public order and safety, later captured in the Hague Conventions. He observed, “The United States acknowledge and protect … religion and morality; strictly private property; the persons of the inhabitants, especially those of women; and the sacredness of domestic relations.”

To guarantee these values and public order, he insisted that civil officials such as judges, police, and municipal government administrators should remain in place, continuing their duties and receiving salaries. In exchange, he concluded that such officials owed an obligation of temporary allegiance to the occupying power.

Occupation Resistance and War-Rebels

Other Lieber Code occupation law provisions cannot be found in or traced to Grotius or Vattel. Rather, they were innovations, created by Lieber for the needs of the Civil War. One example is Article 85’s prohibition on occupation resistance by “war-rebels.”

War-rebels are defined as those “persons within an occupied territory who rise in arms against the occupying or conquering army, or against the authorities established by the same. If captured, they may suffer death … whether called upon to [fight] by their own, but expelled, government or not.”

Notice the “war-rebel” classification: It applies to soldiers—lawful combatants. The Lieber Code defines war-rebels as any who fight in the post-occupation context. These include those acting under the authority of their government, the displaced power. Thus, Lieber required soldiers to give up the hope of driving out the conquering enemy army. If they did not, they would forfeit their privilege as lawful combatants and their entitlement to prisoner of war status if captured.

Remarkable, too, is the fact that the predicate for war-rebel status was the mere fact of occupation regardless of the defeated having agreed to lay down arms. Once a territory had been “conquered,” the people of that territory, including soldiers, were required to accept the fact—even if they themselves have not agreed to any terms with the occupying army.

Cracking the Code on War-Rebels

How did Lieber justify Article 85 and the war-rebel prohibition? Two possibilities occur.

Mitigation of Violence

Lieber observed, “The war-rebel … interferes with the mitigation of the severity of war, which it is one of the noblest objects of the modern law of war to obtain.”[6] He did not explain how war rebels threatened “mitigation of severity.” He may have intended to refer to the severity of the occupation. Occupation policies would likely be harsher if the occupying power were required to deal with resistance—even to the point of reprisals against the population.

More likely, however, Lieber was wary of the civil disorder and possible murderous anarchy that might ensue. Armed resistance presents ample opportunities for lawlessness. Private score-settling, criminal gangs, war lords, terrorists, and totalitarians of various stripes could easily proliferate in the unsettled context of post- or even mid-conflict occupation.

Thirty years earlier, Lieber had read the seminal work On War by his fellow Prussian, Karl von Clausewitz. Clausewitz described the danger presented by popular uprisings. He noted that an uprising by the people can be useful in opposing an invading army. But he cautioned that such uprisings may turn out to be as great a threat to the polity as the invader. Popular uprisings, Clausewitz wrote, can be a “means of revolution, a state of legalized anarchy that is as much of a threat to the social order at home as it is to the enemy.”

Clausewitz’s admonition had particular relevance to the Confederacy. The threat to social order that had been long feared in the South was termed “servile insurrection.” The term described the possibility that its four million enslaved people might rise up and wreak a revengeful havoc on the white population. Leaders in the North also sought to avert such a disruption. Thus, Lieber’s war-rebel provision, according to historian and law professor John Fabian Witt, would facilitate recovery of U.S. territories and would simultaneously restore order and peace. Although Union control of the South would mean emancipation, it would not occasion further uprising.


Concern with honor offers a second explanation for Lieber’s occupation resistance provisions. The Lieber Code consistently addressed the honor of the soldier, steering, for example, between righteous killing in combat and wrongful killing of the surrendered or injured enemy. The war-rebel provision may be seen as guidance in that respect. Lieber implies there is dishonor in the action of the war-rebel who makes “hostile use of the protection which by the modern law of war the victor extends to the persons and property of the conquered.”

The Pre-Lieber War-Rebel

Lieber claimed the war-rebel “has been universally treated with the utmost rigor of the military law.” But neither Grotius or Vattel mention the war-rebel concept. Nor, for that matter, did Lieber’s own 1838 account of the law of war.[7] It is likely the war rebel was a late Lieber invention. That was certainly the view of James Seddon, Secretary of War of the Confederacy: “[N]ot words of an American vocabulary … more what you would expect from a European military despot.”

With his condemnation of the war-rebel, Lieber parted ways with Grotius, Vattel, and Clausewitz. Each recognized that a soldier was not obligated to accept occupation, that he may consider it a temporary setback, something to be reversed by rallying the martial spirit. Indeed, Lieber’s predecessors attached nobility and honor to resistance. Clausewitz maintained that the occupied territory may have been ceded for the very purpose of preserving the armed forces to fight another day.

But resistance, Grotius and Vattel held, was noble only to a point. Eventually, unavailing resistance must cease. Grotius quoted an ancient Hebrew proverb that stated “if there were no sovereign Power, we should swallow up one another live.”

The valorization of peace over civil unrest is perhaps less a humanitarian principle than the simple bias of established States. The experience of occupation in World War II, however, opened minds to the possibility that resistance may in some cases be preferable to civil order, when civil order is the masquerade of murderous tyranny.

The need to resist oppression was apparent to the old authorities, too. Grotius and Vattel both concluded that in extreme cases, when the injustice was unbearable, the people have the right to rise up. Not for small injustices (say, when one European prince displaces another as the ruler of a territory), but for “insupportable oppression,” or an occupation that is “offensive to justice.”

Vattel wrote, “If an unjust and rapacious conqueror subdues a nation, and forces her to accept of hard, ignominious, and insupportable conditions, necessity obliges her to submit: but this apparent tranquillity [sic] is not a peace; it is an oppression which she endures only so long as she wants the means of shaking it off, and against which men of spirit rise on the first favourable opportunity.”

For his part, Grotius wrote, “we must distinguish [therefore] between doubtful or supportable Injustices and manifest or insupportable Injustices. The former are to be born; but strictly speaking, there is no Obligation to bear the latter ….”

Unfortunately, these authorities cannot tell us how to distinguish “insupportable” occupation from the other kind. (Such an inquiry will likely lead back to the old dilemma of jus ad bellum as a standard for the lawfulness of the soldier’s behavior.)


While much of Lieber’s work generated the modern law of armed conflict, including the law of belligerent occupation, Article 85 cannot be counted among them. As Sir Adam Roberts has pointed out, “it cannot be appropriate to declare in advance that all such resistance is a violation of the laws of war,” and the recognition in the Geneva Conventions of 1949 that certain resistance fighters may be lawful combatants is “an advance on Lieber’s view that resistance against occupation is ipso facto a violation of the laws of war.”


Richard Salomon is a Department of Law Visiting Lecturer at the United States Military Academy, West Point, New York, and is the author of The Unsuspected Francis Lieber (2018). Previously, Rick was in private law practice in New York City.



[1] Vattel, Emer de. The Law of Nations, or, Principles of the Law of Nature, Applied to the Conduct and Affairs of Nations and Sovereigns. 1758. Edited by Bela Kapossy and Richard Whatmore. Liberty Fund, 2008.

[2] Grotius, Hugo. The Rights of War and Peace. 1625. Edited by Richard Tuck. Liberty Fund, 2005.

[3] Lieber Code, arts. 21,22,23,24,25,33, and 156.

[4] Lieber Code, arts. 34, 35, and 36.

[5] Lieber Code, arts. 26, 39, and 134.

[6] Lieber, Francis. “Guerrilla Parties Considered with Reference to the Laws and Usages of War.” 1862. Hartigan, Richard S. Military Rules, Regulations and the Code of War: Francis Lieber and the Certification of Conflict. Routledge, 2017, pp 31-44.

[7] Manual of Political Ethics. William Smith, 1838.