Until the nineteenth century, the map of international law looked much like the world maps of the Middle Ages. Those who used such maps sailed into oceans filled with sea monsters, with whole continents missing, and others labeled Terra Incognita. Slavery was accepted. No woman could own property, much less vote. Torture was normal in criminal investigations, and felonies were punishable by death. Mankind lived “on a darkling plain swept with confused alarms of struggle and flight, where ignorant armies clash by night.”

The nineteenth century brought hope of human progress: the abolition of slavery in most of the world, the women's suffrage movement in Europe and America, and with the Red Cross, the beginning of humanitarian laws of war. But it also brought machine guns and colonial domination made more efficient by modern transportation and communication. The 1648 Treaty of Westphalia limited international law to relationships between States and still allowed States to conduct their “internal” or “domestic” affairs without hindrance. States had licenses to hunt down their own citizens with impunity. With few exceptions, individuals were not the subjects of international law.

New monsters arose in the twentieth century. Nazi and Communist regimes murdered more people than all wars combined. Two World Wars threatened the very foundations of human civilization and opened the era of Total War, when distinctions between combatants and civilians dissolved. On August 6 and 9, 1945, nuclear attacks on Hiroshima and Nagasaki incinerated 200,000 civilian lives in just three days.