There have always been laws of war. Individual armies have their own laws that determine how their military actions will proceed, what is off limits and what is allowed, and "rules of engagement" that dictate the way they initiate battle. Throughout history, opposing nations have established ground rules for war, but until the nineteenth century, these rules applied only to a particular conflict and the countries it involved. Once that war was over, the rules were discarded.
With the 1864 Geneva Convention, the rules of war became an international matter. The laws that came out of Geneva and The Hague transcend any specific conflict. They attempt to "diminish the severity and disasters of war" (Hague IX) in general, applying to armed conflicts across the board.
The Geneva Conventions
Made official in 1949 and ultimately adopted by 190 countries, the Geneva Conventions establish the rules for the treatment of the "victims" of war -- wounded or sick soldiers, prisoners of war, and civilians.
The Geneva Conventions as we now know them were established in 1949, after World War II. But the first Geneva Convention was actually held in 1864. That first conference established a set of rules to protect wounded and sick troops on the field.
The initial 1864 treaty was initiated by an organization called the International Committee for Relief to the Wounded. This organization is now called the International Committee of the Red Cross. The Red Cross was originally established to provide medical care to those wounded in battle. It was created by Henry Dunant, who was traveling through Italy after the 1859 Battle of Solferino and saw dying soldiers left untreated. He asked civilians to help him gather and treat the wounded and insisted they not discriminate based on nationality. The Red Cross was founded on the belief that all soldiers, regardless of which army they belong to, should receive medical treatment.
That first treaty was amended and built upon in subsequent meetings, culminating in 1949 when nations gathered to address the horrors of WWII. The 1949 assembly resulted in the adoption of four Geneva Conventions:
The Hague Conventions
Conferences regarding the international rules of war were held in The Hague, the Netherlands, in 1899, 1907 and 1954. Dubbed the International Peace Conferences, these meetings produced numerous rules, or conventions, that loosely fall into the categories of combat, weaponry, property rights and the duties of neutral countries.
The first two Hague conventions, the 1899 Hague Peace Convention and the 1907 Hague Convention on Land Warfare, are largely similar, the latter expanding and adding to the initial Hague sections on combat laws, illegal weaponry and financial concerns. Another conference was scheduled and then cancelled with the outbreak of World War I.
The severe destruction of cultural property -- artwork, literature, artifacts -- that occurred during World Wars I and II revealed holes in the existing laws. In 1954, the Hague Convention for the Protection of Cultural Property in the Event of Armed Conflict was signed into effect. This third set of laws addressed the issue of cultural preservation in greater depth than the first two, attempting to protect a nation's identity in the face of war and occupation.
As technology and awareness have progressed, the conventions produced in The Hague and those coming out of Geneva have progressively overlapped: Technological developments in the realm of war tend to threaten humanitarian concerns, and humanitarian concerns tend to want to stem the progress of weapons and methods of destruction. These major treaties comprise some of the most essential laws of war, attempting to protect humanitarian, cultural and financial concerns within a framework that inherently wants to disregard everything but the battle at hand.