Over the years the Americas have made significant contributions to the development of international humanitarian law. These include three nineteenth-century texts which constitute the earliest modern foundations of the law of armed conflict. The first is a treaty, signed on 26 November 1820 by the liberator Simón Bolívar and the peacemaker Pablo Morillo, which applied the rules of international conflict to a civil war. The second is a Spanish-American work entitled Principios de Derecho de Genres (Principles of the Law of Nations), which was published in 1832 by Andrés Bello. This work dealt systematically with the various aspects and consequences of war. The third is a legal instrument, signed on 24 April 1863 by United States President Abraham Lincoln, which codified the first body of law on internal conflict under the heading “Instructions for the Government of Armies of the United States in the Field” (General Orders No. 100). This instrument, known as the Lieber Code, was adopted as the new code of conduct for the armies of the Union during the American Civil War.