the Lieber Code

An order prepared for the Union Army in 1863, during the Civil War, by Professor Francis Lieber of Columbia College as the first codification of standards of the laws of war, or what is now called international humanitarian law. Also known as General Order 100, “Instructions for the Government of Armies of the United States in the Field, ” it became known as “Hague law” after the international standard setting in 1899 of the Hague Regulations.

See the Introduction, Abbreviations and Pronunciation for further details.