Armed conflict broke out between the Empire of Brazil and the United Provinces of the Río de la Plata over control of the Cisplatina Province (roughly present-day Uruguay), setting the stage for later treaty-based border and sovereignty settlements in the Río de la Plata region.
Brazil and the United Provinces signed the Preliminary Peace Convention (often called the Treaty of Montevideo), ending the Cisplatine War and providing for an independent Uruguay—an outcome with major long-term consequences for Brazil’s southern frontier and diplomacy in the Platine basin.
Brazil established its first diplomatic delegation in Venezuela, signaling the Empire’s widening northern diplomatic network even as precise Amazonian boundary definitions remained incomplete.
Brazil and Uruguay concluded a commerce and navigation treaty that addressed regional riverine interests (including the River Plate system), reflecting Brazil’s strategic focus on waterways and influence in the Platine region.
Brazil and Uruguay signed the 1851 Boundary Treaty, fixing key segments of their frontier (including the Quaraí/Cuareim River area) and tying border settlement to Brazil’s broader regional role after intervening in Uruguay’s civil conflict.
Brazil and Peru signed the Herrera–da Ponte Ribeiro agreement in Lima, combining Amazon trade/navigation arrangements with partial boundary understandings (notably using the Tabatinga–Apaporis line and the Javari/Yavarí River as reference points), an early step in formalizing Brazil’s far-western frontier diplomacy.
A “friendship, commerce and navigation” treaty with Paraguay (signed 4 March 1853, as cataloged in British records) illustrates the era’s emphasis on formal instruments governing trade and river access amid unresolved frontier questions in the Paraguay River basin.
Brazil and Venezuela signed the Treaty of Limits and River Navigation (often associated with Caracas), deliminating much of their Amazonian border using watershed divides and river courses—an important northern-border settlement later supplemented by additional protocols.
Paraguayan forces captured the Brazilian steamer Marquês de Olinda on the Paraguay River, a major escalation in riverine and border tensions that helped precipitate full-scale war in the Plata basin.
Brazil, Argentina, and Uruguay signed the Treaty of the Triple Alliance against Paraguay. Beyond wartime coordination, it also outlined postwar objectives including boundary arrangements—making it a pivotal diplomatic document for later frontier settlements.
Brazil and Bolivia signed the Treaty of Ayacucho (Friendship, Limits, Navigation, Commerce and Extradition), establishing a boundary framework in the western Amazon and linking territorial definition to navigation and commercial provisions amid wartime regional pressures.
The Paraguayan War ended in 1870, after which the allies (including Brazil) shifted from wartime diplomacy to resolving occupation, reparations, navigation, and disputed boundaries—especially along the Paraguay and Paraná river systems.
Foreign Relations and Border Treaties (1822–1870)
