How did moral/legal thinking about war especially “just war” evolve from ancient times

how did moral/legal thinking about war especially “just war” evolve from ancient times through the middle ages. How does that relate to Walzers book Just and unjust war? Use Reichberg chapters 1,2,3,5, 7

instructions: cite at least one time per paragraph and you must quote the philosophers not just the editors. When paraphrasing or giving a summary you must give citations, always cite when you refer to something you did not write. you can only use materials that has been uploaded no outside info.