Having explored how ancient States made friends through diplomacy, and how they made faith through treaties, it is now time to turn to the questions of how the rule of law influenced the manner in which war was declared by ancient peoples and whether there were any legal restraints on the conduct of hostilities in antiquity. On first consideration, it would seem fanciful to suggest that ancient States deemed themselves bound by definitive rules of State behavior in wartime. Such an intimation seems counter-intuitive precisely at moments in ancient international relations that values associated with peaceful coexistence between ancient polities were being discarded in favor of notions of national particularism, imperial conquest, or ethnic self-preservation.

This chapter offers, therefore, a second look at the seeming oxymoron of an ancient law of war. The discussion here is divided into two broad themes. The first is how ancient States commenced hostilities with each other. This topic subsumes such matters as what justifications were considered as sufficient to begin a war with another State. Moreover, this part will look at the procedures that ancient States employed to formally declare war. Last to be discussed is how ancient States viewed the legal consequences attendant on a condition of war.

The second theme of the chapter will be the extent to which ancient States observed rules in the actual conduct of warfare.