Global Impact: The Lincoln Administration and the Development of International Law

by Burrus Carnahan, Professorial Lecturer in Law at the George Washington University Law School and member of President Lincoln’s Cottage’s Scholarly Advisory Group.

In April 1863, President Lincoln approved a War Department order that has had international influence to the present day. Entitled “Instructions for the Government of Armies of the United States in the Field,” after presidential approval it was issued by the U. S. Army as General Orders No. 100, April 24, 1863. General Orders No. 100 did not resemble most military orders. Instead it was a short handbook for the guidance of Union officers on the international laws and customs of war as they existed in the mid-nineteenth century.[1]

The Lincoln administration never admitted the legitimacy of the Confederate government in Richmond.  Nevertheless, by early 1862 the U. S. government had decided to apply the international law of war to its conflict with the Confederate States of America. The Confederates, of course, had from the beginning of the war maintained that they were an independent, sovereign nation and that international law necessarily applied to their relations with the United States. The government in Washington was gradually brought around to the Confederate position on the law of war by a combination of diplomatic pressure from neutral nations (primarily Great Britain and France), Confederate threats of reprisal if their men were not treated as prisoners of war, and domestic political pressure (the relatives of captured Federal soldiers wanted to ensure that their sons, brothers and fathers were treated as prisoners of war by the Confederacy).[2]

[teaser]I’m a good enough lawyer in a western law court, I suppose, but we don’t practice the law of nations up there.[/teaser]

This decision by the Lincoln administration gave rise to a new problem. The volunteer officers who commanded almost all of the Federal infantry, artillery, and cavalry had been directly appointed from civilian life by the governors of the states in which these units were raised. Even those who had been lawyers in civilian life typically knew nothing about the laws and customs of war, which were mainly to be found in obscure and bulky academic treatises. As the President himself allegedly remarked to Congressman Thaddeus Stevens, “I’m a good enough lawyer in a western law court, I suppose, but we don’t practice the law of nations up there.”[3] There was, therefore, a definite need for an authoritative summary of the laws and customs of war that could be distributed for the use of Federal officers in the field.

Major General Henry Halleck, General in Chief of the U. S. Army, was among the first to recognize this need.[4] An expert on international law himself, Halleck turned for help to Dr. Francis Lieber of Columbia University, who had earlier provided legal advice to the Federal government on other issues. Lieber had more than a scholarly interest in the laws and customs of war. In 1815, he was a private in the Prussian army during the last campaign against Napoleon, and was severely wounded at the battle of Namur. Unable to find an academic position in the North, Lieber accepted appointment as a professor at South Carolina College, a position he held for twenty years. The Civil War split Lieber’s family. His oldest son, still residing in South Carolina, enlisted in the Confederate army and was mortally wounded at the battle of Williamsburg. His other two sons joined the Union army and one was badly wounded at Fort Donelson.[5]

In the fall of 1862, the War Department appointed Dr. Lieber and four generals to a board to draw up a summary of the laws of war and to recommend changes in the Articles of War (the disciplinary code of the army). It was decided that the generals would tackle the Articles of War, leaving the codification of the laws and customs of war to Dr. Lieber. During his tenure in South Carolina, Lieber had amassed a wide-ranging collection of wartime precedents from European countries. Where the precedents were uniform, he incorporated them in his draft code, even if they appear inhumane to us. For example, he declared that “When a commander of a besieged place expels the noncombatants, in order to lessen the number of those who consume his stock of provisions, it is lawful, though an extreme measure, to drive them back, so as to hasten on the surrender.”[6] Where state practices were in conflict, however, he tended to choose the more humane and civilized practices as precedents.

After minor changes by other members of the board and General Halleck, Lieber’s draft was sent to President Lincoln and eventually published by the War Department as General Orders No. 100. In tribute to its principal author, today it is often referred to as “the Lieber Code.”

Lieber Code copy 1898

1898 reprinting of the “Lieber Code”. Click the image to read a digitized copy.

One of the fundamental themes of the Lieber Code was that the violence of war should be directed only at valid military objectives, and that acts of revenge or cruelty, intended merely to increase the suffering of enemy soldiers or civilians, were prohibited and must be punished.[7] This theme must have resonated with President Lincoln. Throughout his life, Abraham Lincoln had believed that human decisions should be governed by reason rather than emotion.[8] During the Civil War he admonished his generals to be sure they were acting for valid military reasons, not merely for revenge.[9]

Other important rules laid down in the Lieber Code, which have survived in international law to this day, included the following.

Article 19, “Commanders, whenever admissible, inform the enemy of their intention to bombard a place, so that the noncombatants, and especially the women and children, may be removed before the bombardment commences. But it is no infraction of the common law of war to omit thus to inform the enemy. Surprise may be a necessity.”

Article 35: “Classical works of art, libraries, scientific collections, or precious instruments, such as astronomical telescopes, as well as hospitals, must be secured against all avoidable injury, even when they are contained in fortified places whilst besieged or bombarded.”

Article 44: “All wanton violence committed against persons in the invaded country, all destruction of property not commanded by the authorized officer, all robbery, all pillage or sacking, even after taking a place by main force, all rape, wounding, maiming, or killing of such inhabitants, are prohibited under the penalty of death, or such other severe punishment as may seem adequate for the gravity of the offense.”

Article 47: “Crimes punishable by all penal codes, such as arson, murder, maiming, assaults, highway robbery, theft, burglary, fraud, forgery, and rape, if committed by an American soldier in a hostile country against its inhabitants, are not only punishable as at home, but in all cases in which death is not inflicted, the severer punishment shall be preferred.”

Article 70: “The use of poison in any manner, be it to poison wells, or food, or arms, is wholly excluded from modern warfare. He that uses it puts himself out of the pale of the law and usages of war.”

Article 53: “The enemy’s chaplains, officers of the medical staff, apothecaries, hospital nurses and servants, if they fall into the hands of the American Army, are not prisoners of war, unless the commander has reasons to retain them. In this latter case; or if, at their own desire, they are allowed to remain with their captured companions, they are treated as prisoners of war … .”

[teaser]The law of nations knows of no distinction of color[/teaser]

In an era when racism was rampant in the United States, both North and South, perhaps the most radical provision of the Lieber Code was Article 58: “The law of nations knows of no distinction of color, and if an enemy of the United States should enslave and sell any captured persons of their army, it would be a case for the severest retaliation, if not redressed upon complaint.”  After numerous reports that African American soldiers were not being treated as prisoners of war by the Confederacy, President Lincoln issued an order calling for retaliation against Confederate prisoners of war, though it does not appear the threat was ever carried out.[10]

The Lieber Code remained the U.S. army’s standard guidance on the laws and customs of war for fifty years.  In Europe, however, the document had an even greater impact.  In 1874, Czar Alexander II convened an international conference in Brussels to adopt a multilateral treaty codifying the law of land warfare, based on a negotiating text that drew heavily on the Lieber Code.[11]  While the Brussels Conference was unsuccessful in negotiating a binding treaty, efforts to internationalize the Lieber Code continued.  Finally, the 1899 Hague Peace Conference, convened by Czar Nicholas II, adopted a treaty based largely on the Lieber Code.  Slightly revised at the 1907 Hague Peace Conference, the Hague Conventions and their annexed Regulations on the Laws and Customs of War on Land remain the foundation of the modern laws of war.[12]

Czar Nicholas II of Russia convened the 1899 Hague Peace Conference, which adopted a treaty based largely on the Lieber Code.

Czar Nicholas II of Russia convened the 1899 Hague Peace Conference, which adopted a treaty based largely on the Lieber Code.

Even a cursory examination of the Hague Regulations reveals their debt to the Lieber Code.  The obligation to warn the inhabitants of besieged cities before bombardment, “except in cases of assault,” was set out in article 26 of the Regulations.  Article 27 codified the duty to avoid damaging “buildings dedicated to religion, art, science, or charitable purposes, historic monuments, [and] hospitals,” during bombardments.  Pillage was formally prohibited by article 47.  Article 23 prohibited the use of poison as well as refusal to grant quarter to surrendering enemy soldiers.

The Lieber Code also influenced the development of the Geneva Conventions on war victims.  Article 53 foreshadowed the original 1864 Geneva Convention[13] in providing that captured medical personnel are not generally to be retained in custody as prisoners of war, except as needed to treat their own wounded.  The principle is currently reflected in the 1949 Geneva Convention on the Wounded and Sick.[14]

Unfortunately, the Hague Regulations did not incorporate Lieber’s principle that the “law of nations knows of no distinction of color.”  The principle of racial nondiscrimination was not incorporated into treaty law until after World War II.  Article 16 of the 1949 Convention on Prisoners of War provides that “all prisoners of war shall be treated alike by the Detaining Power, without any adverse distinction based on race, nationality, religious belief or political opinions.”[15]  Similarly, Article 13 of the 1949 Geneva Convention on treatment of civilians in time of war provides that it covers “the whole of the populations of the countries in conflict, without any adverse distinction based, in particular, on race, nationality, religion or political opinion”.[16]

President Lincoln had no role in drafting General Orders No. 100, but he almost certainly read it and acted within its spirit, particularly where acts of cruelty or revenge were brought to his attention.  What does seem certain is that he could not have realized that the Lieber Code would be one of the one of the most widespread and long lasting legacies of his administration.


Burrus Carnahan, Esq., is a foreign affairs officer in the Bureau of International Security and Nonproliferation at the U.S. Department of State. He served for 20 years as a Judge Advocate in the U.S. Air Force, where he specialized in the law of war. His service included a tour as Associate Professor of Law at the U.S. Air Force Academy in Colorado where he developed that institution’s first program on the law of war. He has also lectured on air warfare at the International Institute of Humanitarian Law at San Remo, Italy. He was the principal researcher on United States legal practice for the International Committee of the Red Cross study on Customary International Humanitarian Law (Cambridge U. Press, 2005), and is a U.S. correspondent for the Yearbook of International Humanitarian Law, published by the T.M.C. Asser Institute at the Hague, Netherlands. 

Mr. Carnahan is Professorial Lecturer in Law at the George Washington University Law School and is a member of President Lincoln’s Cottage’s Scholarly Advisory Group.


[1] “Instructions for the Government of Armies of the United States in the Field,” April 24, 1863, in The Laws of Armed Conflicts: A Collection of Conventions, Resolutions and other Documents, ed. Dietrich Schindler and Jiri Toman (Rockville, Sijthoff & Noordhoff, 1981), 1-23.

[2] See Burrus Carnahan, Act of Justice: Lincoln’s Emancipation Proclamation and the Law of War (Lexington: University Press of Kentucky, 2007), 61-71

[3] Recollected Words of Abraham Lincoln, ed. Don E. Fehrenbacher and Virginia Fehrenbacher (Stanford, Stanford University Press, 1996), 423.

[4] John F. Marszalek, Commander of All Lincoln’s Armies: A Life of General Henry W. Halleck (Cambridge, Harvard University Press, 2004), 167.

[5] Marszalek, Commander, 168.

[6] Schindler and Toman, “Instructions for the Government of Armies,” Article 19.  A variant of this rule appeared as recently as 1956 in the U. S. Army’s manual on the law of war.  Field Manual 27-10, The Law of Land Warfare (Washington, Department of the Army, 1956), para. 44.

[7] See Schindler and Toman, “Instructions for the Government of Armies,” Article 11 (the law of war disclaims “all cruelty and bad faith” and “all acts of private revenge”), Article 16 (“Military necessity does not admit of cruelty – that is, the infliction of suffering for the sake of suffering or for revenge, nor of maiming or wounding except in fight, nor of torture to extort confessions”), Article 28 (retaliation for enemy violations of the law will “never be resorted to as a measure of mere revenge, but only as a means of protective retribution”), Article 56 (“A prisoner of war is subject to no punishment for being a public enemy, nor is any revenge wreaked upon him by the intentional infliction of any suffering, or disgrace, by cruel imprisonment, want of food, by mutilation, death, or any other barbarity”), Article 60 (“It is against the usage of modern war to resolve, in hatred and revenge, to give no quarter” to an enemy attempting to surrender), Article 68 (“Unnecessary or revengeful destruction of life is not lawful”), Article 71 (“Whoever intentionally inflicts additional wounds on an enemy already wholly disabled, or kills such an enemy, or who orders or encourages soldiers to do so, shall suffer death, if duly convicted, whether he belongs to the Army of the United States, or is an enemy captured after having committed his misdeed”).

[8] See, e.g., “Address Before the Young Men’s Lyceum of Springfield, Illinois,” January 27, 1838, in  The Collected Works of Abraham Lincoln; ed. Roy P. Basler (New Brunswick, Rutgers University Press, 1953), 1:108-115; Michael Burlingame, Abraham Lincoln: A Life (Baltimore, Johns Hopkins University Press, 2008), 1:69-70 (Lincoln prevents his fellow militiamen from killing an unarmed Indian during the Black Hawk War); see also Allen C. Guelzo, Redeeming the Great Emancipator (Cambridge, Harvard University Press, 2016), 83-85.

[9] See, e,g., “to William S. Rosecrans,” November 19, 1864, in Roy P Basler, Collected Works, 8:116. See also Lincoln’s decision to spare the lives of over 260 Sioux warriors who had been sentenced to death merely for participating in battles against U. S. soldiers and Minnesota militia. In context, including protests against clemency from Minnesota officials and white citizens, it appears that these death sentences were acts of revenge rather than punishment for true war crimes. “To the Senate,” December 11, 1862, in Roy P Basler, Collected Works, 5: 550-51.

[10] “Order of Retaliation” July 30, 1863 in Roy P. Basler, Collected Works, 6:357.

[11] “Project of an International Declaration Concerning the Laws and Customs of War,” August 27, 1864, in Schindler and Toman, Laws of Armed Conflicts, 25-34.

[12] “Convention (II) with Respect to the Laws and Customs of War on Land” (1899) and “Convention (IV) Respecting the Laws and Customs of War on Land,” in Schindler and Toman, Laws of Armed Conflicts, 57-87.

[13] “Convention for the Amelioration of the Condition of the Wounded in Armies in the Field,” August 22, 1864, in Schindler and Toman, Laws of Armed Conflicts, 213-35.

[14] “Convention (I) for the Amelioration of the Condition of the Wounded and Sick in Armies in the Field,” August 12, 1949, Article 24, in Schindler and Toman, Laws of Armed Conflicts, 305-30.

[15] “Geneva Convention (III) Relative to the Treatment of Prisoners of War,” August 12, 1949, in Schindler and Toman, Laws of Armed Conflicts, 355-425.

[16] “Geneva Convention (IV) Relative to the Protection of Civilian Persons in Time of War,” August 12, 1949, in Schindler and Toman, Laws of Armed Conflicts, 427-88.

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