This chapter investigates how historically developed social division or social stratification has shaped warfare. It discusses the war is related to specific issues of race, ethnicity, social class, and gender within modern societies interact with armed conflict. The chapter focuses on the various positive and negative effects war has on various groups and whether it assists in strengthening or challenging hierarchical systems of power, wealth, and status. It addresses war crimes, crimes against humanity, wartime genocide, and ethnic cleansing. Sociology and other social sciences have spent centuries attempting to understand the origins of social stratification. Based on sociological theories, the origins of social stratification rest in the creation and maintenance of social class. War and collective violence are powerful tools in creating and maintaining social stratification and inequality. There are also several approaches within warfare that have disproportionately affected various populations around the world.