On this day in history, President Lincoln signed the Instructions for the Government of Armies of the United States in the Field, General Order № 100, popularly known as the Lieber Instructions, because they were prepared by Francis Lieber.
Lieber had fought for Prussia in the Napoleonic Wars and later became a Professor of History and Political Economy at South Carolina College (what later became Columbia University). In 1857 he moved north to Columbia Law School where he taught International Law and Civil and Common Law until his death in 1872. He published his series of lectures on the laws and usages of war as “International Law, or, Rules Regulating the Intercourse of States in Peace and War.”
During the American Civil War, Lieber’s three sons were all serving (two for the Union and one for the Confederacy). While in St. Louis searching for one of his sons who had been wounded, Lieber met Union General Henry Halleck, and when Halleck became General-in-Chief in July, 1862, Halleck solicited Lieber’s views on some of the knottier questions presented by war. Secretary of War Edwin Stanton also looked to Lieber for advice. Thus Halleck and Stanton decided to invite Lieber to Washington to sit on a committee to revise the 1806 Articles of War.
The standards were deemed necessary because the large armies required by the Civil War were made up mostly of untrained volunteers, and often commanded by officers who had no familiarity with established military procedure, rights and duties of officers, treatment of soldiers and civilians, and so on. A lot of confusion and conflicting orders were issued, which frequently had to be rescinded.
Lieber did most of the writing for the new set of rules for armies in the field, and Halleck edited the draft to make sure nothing conflicted with Lincoln’s policies. Then Lincoln issued them on this day in history.
The document included considerations for ethical behavior, insisting on humane treatment of civilian populations in occupied areas. It was the first expressly codified law that forbade giving “no quarter” to the enemy (i.e., killing prisoners of war), except in such cases when the survival of the unit that held these prisoners was threatened. It forbade the use of poisons, stating that use of such puts any force who uses them entirely outside the pale of the civilized nations and peoples; it forbade the use of torture to extract confessions; it described the rights and duties of prisoners of war and of capturing forces. It described the state of war, the state of occupied territories, the ends of war, and discusses permissible and impermissible means to attain those ends; it discussed the nature of states and sovereignties, and insurrections, rebellions, and wars.
The Lieber Code also defended the lawfulness of Emancipation under the laws of war and insisted that those same laws prohibited discrimination on the basis of color among combatants.
European jurists and treaty negotiators picked up Lieber’s text and used it as the basis for negotiations that ultimately formed the basis of the Hague Conventions of 1899 and 1907. Some of its harsher measures were abolished by the Third and Fourth Geneva Conventions, however.
You can read the full text of the Lieber Code here.