The Paraguayan War has important consequences for Brazil and the Rio de la Plata region.

It leaves Brazil and Argentina facing each other over a prostrate Paraguay and a dependent Uruguay, a situation that will soon turn into a tense rivalry that will repeatedly assume warlike postures.

Historians debate the number of Paraguayan casualties, some asserting that fifty percent of Paraguayans were killed, others arguing that it was much less, possibly eight to nine percent of the prewar population total.

Nonetheless, the losses from battle, disease, and starvation are severe and disrupt the development of the republic.

In Brazil the war had contributed to the growth of manufacturing, to the professionalization of the armed forces and their concentration in Rio Grande do Sul, to the building of roads and the settling of European immigrants in the southern provinces, and to the increased power of the central government.

Most important for the future, the war had brought the military firmly into the political arena.

Military officers are keenly aware that the war had exposed the military's lack of equipment, training, and organization.

Officers blame these shortcomings on civilian officials.

In the next decades, reformist officers seeking to modernize the army will criticize the Brazilian political structure and its peculiar culture as obstacles to modernization.