This chapter develops the main arguments of the book, focusing on how belligerents in interstate and civil war have reacted to the development of the laws of war detailed in Chapter 2. States involved in interstate war are perversely incentivized to evade the laws of war as these laws have proliferated. Thus, they are decreasingly likely to engage the formalities of war, specifically declarations of war and peace treaties. Secessionist rebel groups fighting civil wars aim to please the international community, and therefore are decreasingly likely to declare independence formally, generally likely to avoid targeting civilians, and increasingly likely to conclude peace treaties.