The history of political events is made by people. From wars to elections to political protests, the choices we make, our actions, how we behave, dictate events. Not all individuals have the same impact on our world and our lives. Some peoples' choices alter the pathways that history takes. In particular, national chief executives play a large role in forging the destinies of the countries they lead. Why Leaders Fight is about those world leaders and how their beliefs, world views, and tolerance for risk and military conflict are shaped by their life experiences before they enter office - military, family, occupation, and more. Using in-depth research on important leaders and the largest set of data on leader backgrounds ever gathered, the authors of Why Leaders Fight show that - within the constraints of domestic political institutions and the international system - who ends up in office plays a critical role in determining when and why countries go to war.