If one is looking for the mechanism connecting war to state formation in Latin America, the obvious place to start is the Paraguayan War (1864-1870), the single most deadly war in the history of the region. This chapter provides the most detailed discussion of this case in the state formation literature and a narrative covering state formation in the River Plate Basin (i.e., Argentina, Brazil, Paraguay, and Uruguay). I discuss how earlier, lower intensity wars affected the balance between central and peripheral elites and take a brief detour to cover the effect of the Siege of Montevideo on Uruguayan politics, potentially explaining the current Uruguayan exceptionalism in terms of its state capacity levels. I then illustrate how preparation for war led to incipient state formation amidst polarization in all contenders of the Paraguayan War and discuss the war itself, illustrating how the result of contingent battles affected the domestic fate of the state formation. Finally, I discuss how war transformed political parties and the military, two key institutions, setting the basis for long term state capacity growth in the allies, and its decline in Paraguay.

This chapter uses documents and methods from both traditional political history and social history to argues that the origins of the Paraguayan War (1864–1870) can be identified in tensions surrounding the abolition of slavery in Uruguay in the 1840s and the definitive ban of the Atlantic slave trade to Brazil in 1850. These tensions were at play in the disputes over the consolidation of local nation-states and are central to an understanding of the historical process that fed into the Paraguayan War. By the early 1860s they would reach a point of no return. This argument places slavery and Black agency at the center of Brazil’s nineteenth-century international relations, breaking a silence carefully constructed by statesmen and diplomats of the Brazilian Empire.

This chapter uses documents and methods from both traditional political history and social history to argues that the origins of the Paraguayan War (1864–1870) can be identified in tensions surrounding the abolition of slavery in Uruguay in the 1840s and the definitive ban of the Atlantic slave trade to Brazil in 1850. These tensions were at play in the disputes over the consolidation of local nation-states and are central to an understanding of the historical process that fed into the Paraguayan War. By the early 1860s they would reach a point of no return. This argument places slavery and Black agency at the center of Brazil’s nineteenth-century international relations, breaking a silence carefully constructed by statesmen and diplomats of the Brazilian Empire.