In order to convert a frontier into an economically productive, taxpaying territory and its indigenous occupants into laborers, nineteenth-century states had to maintain a “monopoly of violence.” I will illuminate both material and discursive dimensions of this hegemonic process through a detailed study of methods of coercion and instances of colonial violence in the northern Argentine territories of Chaco and Formosa. Multi-archival research in Buenos Aires and several northern provinces will provide a comprehensive history of violence in the Chaco over a period bookended by two of the continent’s most destructive wars: the War of the Triple Alliance, which pitted Paraguay against Brazil, Argentina, and Uruguay (1864-1870), and the Chaco War between Paraguay and Bolivia (1932-1935). I will situate the Chaco’s history in comparative perspective and illuminate the international context that informed Argentine policies. Subsequent chapters will look beyond inter-state dynamics to consider continuities of violence in daily interactions between indigenous people and government officials, capitalists, soldiers, missionaries, and settlers. My dissertation proposes a new approach to the study of comparative settler colonialism, using methods from ethnohistory to show how struggles over the control of violence mapped onto struggles over competing versions of history.