The international law of armed conflict (jus in bello) has undergone a long course of development. Its first traces date from antiquity, but we find a more substantial evolution during the latter part of the Middle Ages.
One of the remarkable elements in this development was the «Code of Chivalry». Although this was not a written document, being transmitted only by tradition, it possessed great authority. It prescribed that combat must take place in such a manner as not to compromise the honour of the knight and condemned unnecessary killing and killing by treachery. It required that the vanquished be treated with generosity and that assistance be rendered to the helpless and destitute.