How do states win wars against other states? We have three explanations. By selection, states enter more winnable wars. By warfighting, states use negative inducements so enemies fear fighting. By peacemaking, states use positive inducements so enemies hope for settling. This dissertation investigates peacemaking. It theorizes that states optimally produce influence only if they efficiently combine warfighting negative and peacemaking positive inducements. It hypothesizes that using some peacemaking on average improves outcomes verses using none. The dissertation tests this with a statistical analysis that measures peacemaking as law of war compliance and estimates effects on all inter-state outcomes from 1899 to 1991. It finds that compliance likely on average improves immediate military and final political relative outcomes. This dissertation also tests peacemaking in four case studies from the Franco-Prussian War of 1870-1871 and World War II. These case studies find that state peacemaking to enemy states, allies, leaders, troops, and civilians probably on average improves absolute war outcomes. These complementary and independent empirical results provide unprecedented support for the peacemaking explanation of how states improve inter-state war outcomes. To succeed, states should be prudent by selection, fierce in warfighting, and principled for peacemaking. / Government