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With so much attention being focused these days on the anniversaries of events during wars of America’s past — particularly the Civil War, The Legal Genealogist pauses once again to consider the laws of war. We’ve already looked at the codes governing the conduct of members of the military in the context of their military duties;1 today, let’s look at the laws of war itself — the laws governing how war could and should be conducted.

General Orders No. 100, 1863

Now the idea that there even could be laws of war may seem a little strange, but it’s surely nothing new. Just read Deuteronomy and you’ll see that it was considered just to “smite every male (of an enemy city) with the edge of the sword” in order to take “the women, and the little ones, and the cattle, and all that is in the city.”2

But, the warriors were admonished:

When thou shalt besiege a city a long time, in making war against it to take it, thou shalt not destroy the trees thereof by forcing an axe against them: for thou mayest eat of them, and thou shalt not cut them down (for the tree of the field is man’s life) to employ them in the siege:

Only the trees which thou knowest that they be not trees for meat, thou shalt destroy and cut them down; and thou shalt build bulwarks against the city that maketh war with thee, until it be subdued.3

By the 17th century, the Dutch jurist Hugo Grotius wrote at length about acceptable conduct during warfare in three volumes entitled De jure belli ac pacis libri tres (On the Law of War and Peace: Three books).4 Grotius’ work colored the attitudes of his day and drove the shift away from scorched earth policies to a more humane view of how the military should behave on the battlefield, to prisoners, and to noncombatants.

That shift can be seen in the early years of the United States as well. As early as 1786, the Second Continental Congress ratified a Treaty with Prussia that expressly provided for rules of engagement should America and Prussia ever find themselves at war.5 It provided in part:

And all women & children, scholars of every faculty, cultivators of the earth, artizans, manufacturers and fishermen unarmed and inhabiting unfortified towns, villages or places, & in general all others whose occupations are for the common subsistence & benefit of mankind, shall be allowed to continue their respective employments, & shall not be molested in their persons, nor shall their houses or goods be burnt, or otherwise destroyed, nor their fields wasted by the armed force of the enemy, into whose power, by the events of war, they may happen to fall; …6

In those early years and through the War of 1812, prisoner treatment and exchanges were generally governed by treaty, rather than statutes or military codes.7

And then came the Civil War. That bloodiest of wars, pitting brother against brother, saw the development of a detailed code, called the Lieber Code after its principal author Francis Lieber. It was ultimately issued on 24 April 1863 by President Lincoln as General Orders No. 100, Instructions for the Government of Armies of the United States in the Field.8

It was a revolutionary document, designed as a guide to rules of engagement — how to fight a war, as opposed to how to act like a soldier. It built on Grotius’ earlier work, and set the legal framework that persists to this day to govern behavior on the battlefield, towards prisoners of war, and towards enemy civilians and noncombatants. Its provisions were extensive — the code had 157 articles, broken down into 10 sections ranging from martial law to assassinations to treatment of spies.

And those provisions were remarkably humane. General Orders No. 100 declared in part:

…as civilization has advanced during the last centuries, so has likewise steadily advanced, especially in war on land, the distinction between the private individual belonging to a hostile country and the hostile country itself, with its men in arms. The principle has been more and more acknowledged that the unarmed citizen is to be spared in person, property, and honor as much as the exigencies of war will admit.

Private citizens are no longer murdered, enslaved, or carried off to distant parts, and the inoffensive individual is as little disturbed in his private relations as the commander of the hostile troops can afford to grant in the overruling demands of a vigorous war.9

As to prisoners, General Orders No. 100 contained a number of key provisions:

     • “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.”10

     • “Prisoners of war are subject to confinement or imprisonment such as may be deemed necessary on account of safety, but they are to be subjected to no other intentional suffering or indignity. The confinement and mode of treating a prisoner may be varied during his captivity according to the demands of safety.”11

     • “Prisoners of war shall be fed upon plain and wholesome food, whenever practicable, and treated with humanity.”12

     • “Every captured wounded enemy shall be medically treated, according to the ability of the medical staff.”13

What’s remarkable about General Orders No. 100 is that the document was adopted, nearly word for word, by the Confederacy, only substituting Confederate States for United States in the text.14

And what’s even more remarkable is that that code preceded, by more than a year, the very first Geneva Convention governing the treatment and care for the wounded and prisoners of war.15

So as we spend the next weeks and months as genealogists, reading the records our ancestors left in their wars, let’s keep the legal framework governing their conduct in mind. It may very well explain why something was done the way it was done… or the consequences when it wasn’t done the way it should have been done.


  1. Judy G. Russell, Busted: Cashiered and conscripted, posted 19 Jun 2012, The Legal Genealogist ( : accessed 2 Jul 2012).
  2. Deuteronomy 20:13-14.
  3. Deuteronomy 20:19-20.
  4. See William Whewell, editor and translator, Hugonis Grotii, De Jure Belli ac Pacis Libri Tres (Cambridge, England : John W. Parker, 1853); digital images, Google Books ( : accessed 2 Jul 2012).
  5. “A Treaty of Amity and Commerce between His Majesty the King of Prussia, and the United States of America,” ratified 17 May 1786, 8 Stat. 84.
  6. Ibid., Article XXIII, 8 Stat. 94-96.
  7. See e.g. “A Provisional Agreement, for the Exchange of Naval Prisoners of War made and concluded at Halifax”; html version, Yale Law School, Avalon Project ( : accessed 2 Jul 2012); citing Hunter Miller, Treaties and Other International Acts of the United States of America (Washington, D.C. : Government Printing Office, 1931).
  8. Instructions for the Government of Armies of the United States in the Field,” issued as General Orders No. 100 by President Lincoln, 24 Apr 1863; html version, Yale Law School, Avalon Project ( : accessed 2 Jul 2012).
  9. Ibid., Art. 22-23.
  10. Ibid., Art. 56.
  11. Ibid., Art. 75.
  12. Ibid. Art. 76.
  13. Ibid., Art. 79.
  14. Scott R. Morris, “The Laws of War: Rules by Warriors for Warriors,” Army Lawyer (Dec. 1997) 4-14.
  15. Wikipedia (, “First Geneva Convention,” rev. 30 May 2012.
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