Even in the brutal world of ancient warfare, both Greeks and Romans recognized an unwritten set of customs and nascent laws that governed their conflicts. This was a rudimentary form of international law, covering everything from the formal declaration of war to the treatment of prisoners and the sanctity of ambassadors. Violating these norms was not just a strategic error but often a religious offense. This episode investigates the ancient laws of armed conflict. We explore the Greek customs surrounding the recovery of the dead for burial after a battle and the Roman religious rituals performed by the Fetial priests to ensure a "just war." We examine the different legal statuses of prisoners: some were ransomed, some were exchanged, and many more were enslaved. We also discuss the absolute legal protection afforded to heralds and ambassadors. While these rules were often broken, their very existence demonstrates an attempt to impose a degree of order and morality on the chaos of war. They represent the earliest efforts to create an international community governed by shared principles. These customs were the distant ancestors of the modern Geneva Conventions.