The laws of war were born of confrontation between armed forces on the battlefield. Until the mid-nineteenth century, these rules remained customary in nature, recognised because they had existed since time immemorial and because they corresponded to the demands of civilisation. All civilisations have developed rules aimed at minimising violence – even this institutionalised form of violence that we call war – since limiting violence is the very essence of civilisation.

By making international law a matter to be agreed between sovereigns and by basing it on State practice and consent, Grotius and the other founding fathers of public international law paved the way for that law to assume universal dimensions, applicable both in peacetime and in wartime and able to transcend cultures and civilizations. However, it was the nineteenth-century visionary Henry Dunant who was the true pioneer of contemporary international humanitarian law. In calling for “some international principle, sanctioned by a Convention and inviolate in character” to protect the wounded and all those trying to help them, Dunant took humanitarian law a decisive step forward. By instigating the adoption, in 1864, of the Geneva Convention for the amelioration of the condition of the wounded and sick in armed forces in the field, Dunant and the other founders of the International Committee of the Red Cross laid the cornerstone of treaty-based international humanitarian law.

This treaty was revised in 1906, and again in 1929 and 1949. New conventions protecting hospital ships, prisoners of war and civilians were also adopted.