In this chapter, I provide the beginnings of a normative grounding for the rules of war, as well as for war crimes prosecutions for violations of international humanitarian law. I focus on the need for all States that go to war – those that have just cause to do so and those that do not – to instill restraints in their soldiers. Such restraints are best if grounded in the idea of honor that soldiers qua soldiers should display while fighting. I draw on the work of Hugo Grotius on honor and Samuel Pufendorf on collective responsibility. A State has a collective responsibility to provide and enforce the rules of war. I will argue that a State's soldiers represent the interests of the State and the State needs to make sure that soldiers are acting within reasonable bounds – that is, honorably. More importantly, the rules of war also protect soldiers, and the State owes such protection to those men and women made vulnerable when they are sent off to war to protect the State's interests. It is also a legitimate interest of the international community to reinforce such norms through international prosecutions for war crimes violations, although this is not the only way that such norms can be reinforced.