Short answers, pulled from the story.
The Battle of Solferino in northern Italy in 1859 led to the creation of international humanitarian law. Henry Dunant witnessed 40,000 soldiers dying without medical care and organized local villagers to help them. This event inspired the founding of the International Committee of the Red Cross in 1863.
The Lieber Code was issued in 1863 by order of President Abraham Lincoln. It was drafted by Francis Lieber, a German immigrant and legal scholar. The code forbade the execution of prisoners of war and mandated the humane treatment of civilian populations.
The four Geneva Conventions of 1949 have achieved universal participation with 194 parties. These conventions apply to almost any international armed conflict. They form the legal basis for protection and humanitarian assistance carried out by impartial organizations like the International Committee of the Red Cross.
The Law of The Hague emerged from conferences in 1899 and 1907 and focused on the rights and duties of belligerents and the means and methods of warfare. The Law of Geneva originated from the humanitarian impulse to protect those hors de combat such as the wounded, sick, and shipwrecked. These two streams merged in the 20th century to govern all aspects of armed conflict.
The international community adopted the Convention on the Prohibition of the Use, Stockpiling, Production and Transfer of Anti-Personnel Mines and on their Destruction, also known as the Ottawa Treaty, in 1997. This treaty aims to ban weapons that cause deaths and injuries long after conflicts have ended. An estimated 98% of the victims of these weapons are civilians.