Cisplatine War - 1825-1828

War between Argentina and the Empire of Brazil grew out of the latent colonial rivalry between Spain and Portugal over control of the Banda Oriental, territory comprising present day Uruguay.

In the year 1806 Great Britain being at war with Spain, a fleet was dispatched to the Rio de la Plata, under Sir Home Popham, who attacked Montevideo but was repulsed. A second attempt, made in the year following with a stronger force, was more successful, and on January 23, 1807, the British captured the fort of Montevideo after a siege of eight days. They were obliged, however, to evacuate their position a few months later when General Whitelocke was defeated at Buenos Aires.

The movement for independence in Uruguay began with the declaration of independence at Buenos Aires on May 23, 1810. Uruguay was declared a part of the United Provinces of Rio de la Plata and on May 18, 1811, the Spanish troops were defeated and utterly routed by the Uruguayan general, Jose Artigas.

Portuguese forces seized the area after the defeat in early 1817 of the army led by José Gervasio Artigas, Uruguay's erstwhile independence leader who also had participated in the struggle for Argentine independence. Following its independence from Portugal in 1822, Brazil was confronted by unrest in the Banda Oriental. Relations between Argentina and Brazil remained tense over the ensuing years and deteriorated precipitously after 1824, when bilateral negotiations for the creation of an independent Uruguayan nation were broken off.

Brazil claimed the territory of Uruguay, and sending a strong force to occupy the country, took posession of it, and on May 9, 1824, the Emperior of Brazil declared the territory to be incorporated into Brazil as the Cisplatine Province. On April 19, 1825, a group of Uruguayan revolutionaries (the famous Thirty-Three Heroes) led by Juan Antonio Lavalleja, reinforced by Argentine troops, crossed the Rio de la Plata from Buenos Aires and organized an insurrection that succeeded in gaining control over the countryside.

The April 1825 invasion of the Banda Oriental launched from Argentine territory by a group of Uruguayan patriots, the Thirty- Three Immortals (also sometimes referred to as the Thirty- Three Easterners, or Orientals), sparked an insurgent movement in the disputed area as they were joined by several thousand supporters. Acrimonious charges were leveled by Brazil that Argentina had provided material support for the invasion.

By May 1825 war seemed imminent. The Argentine government, however, had by then neither a standing army nor a naval force at its disposal. During the years of political chaos and civil war that followed independence, both military bodies had fallen apart. On May 31 a new national army was organized, with a general staff, four infantry battalions, six cavalry regiments, an artillery battalion, and a company of engineers. Each of the nation's nine provinces was called upon to send a complement of soldiers proportionate to the size of its population, which was to be determined by the national government.

On the eve of battle a naval squadron commanded by the Irishborn Admiral Guillermo Brown was organized. Supreme command over both forces rested with Argentina's first national president, Bernardino Rivadavia.

The bulk of the inhabitants of the country resisted the Brazilian annexation and declared themselves independent. On August 25, 1825, in a town in the liberated area, representatives from the Banda Oriental declared the territory's independence from Brazil and its incorporation into the United Provinces of the Rio de la Plata. Ably assisted by the government of Buenos Aires they defeated the Brazilian troops on October 12, 1825.

In December 1825 Brazil declared war on Argentina for allegedly having broken its neutrality in aiding the Uruguayan insurgents, a claim denied by the Argentine government. During the first year of the conflict, most of the battles occurred at sea as the small, poorly equipped navy sought to break Brazil's blockade of the port of Buenos Aires. The army remained in a state of disarray, however. Nearly half its 8,000 troops had been forcibly recruited and were unwilling and unprepared to fight. There was also a severe shortage of weaponry. Of the 1,331 carbines reported in the Argentine arsenal in January 1826, only 54 were serviceable.

The Argentine forces were at a disadvantage in the face of the better trained and equipped Brazilian military, yet they were soon able to win many of the war's battles. Contributions collected by the national government from the Argentine population initially enabled the Argentine army and navy to equip themselves. Subsequently the Argentines were able to confiscate weapons and equipment from fallen or retreating Brazilian forces. At the Battle of Juncal in February 1827, the Argentine navy was said not only to have beaten the Brazilian naval squadron it engaged but also to have incorporated into its own fleet the defeated Brazilians' remaining ships. Later that same month the war's major land battle, the Battle of ItuzaingO, was fought and won by the Argentine army.

The conflict lasted nearly three years until its mediated settlement resulted in the creation of Uruguay as an independent buffer state between the two rival powers. In 1828 Lord John Ponsonby, envoy of the British Foreign Office, proposed making the Banda Oriental an independent state. Britain was anxious to create a buffer state between Argentina and Brazil to ensure its trade interests in the region.

With British mediation, Brazil and Argentina signed the Treaty of Montevideo at Rio de Janeiro on August 27, 1828, whereby Argentina and Brazil renounced their claims to the territories that would become integral parts of the newly independent state on October 3. However, Argentina and Brazil retained the right to intervene in the event of a civil war and to approve the constitution of the new state.

Under the terms of peace agreed to in mid-1828, both countries were to withdraw their military forces over a two-month period and pledged to guarantee Uruguay's independence for the next five years. Britain, the mediator and a not wholly disinterested party to the dispute, managed to keep Argentina from annexing Uruguay and thus to prevent it from controlling the Rio de Ia Plata estuary.

Both Brazil and the Argentine Republic recognized the independence previously declared in La Florida by the Uruguayan patriots. Argentine and Brazilian troops began their withdrawal, while a constituent assembly drew up the constitution of the new country, created its flag and coat of arms, and enacted legislation. A constitutional congress met in November of the same year and appointed General Rondeau provisional governor.

The constitution was approved officially on July 18, 1830, after having been ratified by Argentina and Brazil. It established a representative unitary republic—the Republica Oriental del Uruguay (Oriental Republic of Uruguay), the word oriental (eastern) representing the legacy of the original designation of the territory as the Banda Oriental. The constitution restricted voting, made Roman Catholicism the official religion, and divided the territory into nine administrative jurisdictions known as departments. General Fructuoso Rivera was elected the first President and inaugurated on November 6 of the same year.