Thread by @bonesoflasalle

Argentina & Brazil have a long history of not getting along.
However, they have rarely actually gone to war with each other. But, it has happened & one such occasion was the Cisplatine War of the 1820's. It saw the two countries square off over where the border was between them.>

The area in question is known as Cisplatina, meaning the area of the River Plate or Rio de la Plata. Spain 🇪🇸 & Portugal 🇵🇹 had been rather unclear on where the border was between Brazil & Argentina but Portugal solved it by marching in & occupying the territory in 1811. 👉🏻

Brazil became independent & considered the region Brazilian but the local populace was divided. Many felt more akin to the
Argentines than Brazilians, others favored neither side. Argentina, though they denied it at first, naturally backed the separatists who wanted to join them.

A local government was established as well as a military force of volunteers both led by General Juan Antonio Lavalleja. He moved to besiege the Brazilian garrison in Montevideo. Each side put some points on the board but neither scored a decisive success. 👉🏻

Brazilian General Bento Manuel Ribeiro was sent to deal with some of these dissidents, which he did, but with such ease that he thought the commander in Montevideo was just being dramatic. He decided to press on and basically win the war on his own. It didn't work out that way.👉🏻

At the Battle of the Rincón on September 24, 1825 a small force of 270 Uruguayans led by Fructuoso Rivera, defeated a force of 700 Brazilians in a surprise attack. Rivera went on to defeat more Brazilian detachments, attacking isolated units before they could join forces. 👉🏻

Now, the war became official with Argentina 🇦🇷 openly intervening. On the naval front, Brazil 🇧🇷 had Argentina vastly outmatched. Brazil's brown water navy was led by Englishman James Norton while Argentina's navy won some early victories under their Irish Admiral William Brown.

An Argentine army led by General Carlos María de Alvear marched into the Cisplatina & began winning a string of minor victories. Brazilian Emperor Pedro I then launched a counteroffensive he hoped would be decisive. The result was the 1827 Battle of Ituzaingó.

The Battle of Ituzaingó was a grueling 6-hour clash between (roughly) 6,000 Brazilians & 8,000 Argentines. The Brazilian army was also exhausted but was ordered into battle to attack the Argentines anyway. The outcome, not surprisingly, was a major victory for Argentina. 👉🏻

Argentina was stymied at sea, Brazil was stymied on the land. So, with neither side gaining a decisive advantage, they agreed to negotiations for peace. These ultimately resulted in a peace agreement and the creation of the independent republic of Uruguay 🇺🇾.