The causes that led
King John VI of the United Kingdom of Portugal, Brazil and the Algarves, whose court had been installed in
Rio de Janeiro since 1808, to embark on the invasion of the Banda Oriental can be divided into general and circumstantial. Among the first is located in the main place, the former Portuguese aspiration to bring the frontiers of Brazil to the coast of Río de la Plata (), arguing that it matched the
Tordesillas line by which Spain and Portugal had divided the world in 1494. For that reason, the region of the Rio de la Plata was a border area between Spain and Portugal, and as such, a highly conflictive area and theater of bloody battles over the centuries, even after the American colonies became independent of the European powers. The Río de la Plata was strategic because it is the starting point of a large river basin, the fifth in the world, that goes to the heart of South America, from near mining areas in Potosí (current Bolivia), through Paraguay, Mato Grosso and reaching São Paulo. Additionally, the Banda Oriental, in the eighteenth and early nineteenth centuries, was an area of major agricultural wealth, which was organized on the old dairy and beef production, a staple of African slaves who constituted the Brazilian economic base Following that line of historical conflict,
Buenos Aires was founded in 1536 to prevent the Portuguese from extending beyond the Río de la Plata. During the period between 1580 and 1640, in which the Kingdom of Portugal was part of the
Iberian Union together with the Kingdom of Spain under the "Catholic Monarchy", Spain relaxed precautions on the ill-defined borders between the two kingdoms, a circumstance that Portugal took to expand the territory of Brazil, to the west and south. In 1680 the Kingdom of Portugal founded the
Colonia del Sacramento (), the first settlement in what is now Uruguay, right in front of Buenos Aires, on the other bank of the Rio de la Plata. Since then several clashes occur and precarious agreements between the Portuguese and Spanish in the Banda Oriental and the Misiones. Portugal also took the troubled political circumstances produced from Napoleon's invasion of Spain in 1808, introducing the Princess Carlota Joaquina, wife of John VI and sister of King Ferdinand VII, captive of Napoleon, as the best alternative to protect the interests of Spanish crown. However, the common struggle against Napoleon Bonaparte, who invaded Spain in order to attack Portugal, as their government disregarded the
Continental System imposed on them by France, led Portugal to avoid a disagreement with Spain and the occupation projects were delayed. The occupation of the
Misiones Orientales () in 1801 by Portuguese troops, commanded by
bandeirante José Francisco Borges do Canto and attempts to generate a protectorate during the crisis of 1808, were closer antecedents. The crisis began when the governor of Montevideo
Francisco Javier de Elío came into conflict with the Viceroy of the Río de la Plata,
Santiago de Liniers, who came to the political break with the constitution of the Junta of Montevideo on 21 September that year. The Portuguese monarchy took advantage of the situation by sending the military and diplomatic Joaquín Javier Curado to offer, in terms restraining orders, acceptance of the protectorate in the Banda Oriental on the argument the preserve it from a Viceroy considered "Afrancesado". Elio rejected the offer at first, but the course of political events from the 1810 May Revolution in Buenos Aires allowed the Portuguese, on two occasions, to attempt armed seizure of the territory. Those times were 1811 and 1816. The
Portuguese invasion of 1811, was the result of a request by then viceroy of Río de la Plata, Francisco Javier de Elio, in support of the Spanish authorities against Artiguist revolutionaries. This invasion took place in the context, as already mentioned, of the May Revolution, where the influence of the same Elío established the capital of the Viceroyalty of the Río de la Plata in Montevideo, thereby becoming viceroy. The revolution had infiltrated in the Banda Oriental after the Cry of Asencio. José Rondeau and José Artigas commanded the troops that, after the Battle of Las Piedras, besieged Montevideo on May 21, 1811. Elio, despite being besieged and in considerable difficulty, managed to block with a royalist naval fleet the port of Buenos Aires and called for help from the Portuguese. A month later, in July, was dispatched from Rio de Janeiro to the south an army of 4,000 men under General Diogo de Sousa. Defeated in Paraguay and Upper Peru, and stopped by the Elio naval blockade, the government of Buenos Aires sought an agreement with Montevideo in exchange for removing the naval blockade and the withdrawal of the Portuguese. The Artiguistas rejected the deal, which left them helpless against the enemy, and followed Artigas in the episode known as the Oriental Exodus. The Portuguese troops had not left the eastern territory until August 1812 when, with the support of the British government, Buenos Aires ensured compliance of the 1811 Armistice Agreement, through the Rademaker-Herrera deal of 1812. The context of 1816, with the state of war between the Orientals and Buenos Aires (which virtually ensured the neutrality, at least, the neutrality of Buenos Aires to the occupation of the Oriental territory) and the European context, marked by the absolutist restoration that denied the colonies their right to independence from the monarchies (which guaranteed Portugal against any hostile reaction from Spain), proved ideal for the realization of the old goal. Those were the main circumstances. The ailing Portuguese royal family that had emigrated to Rio de Janeiro in 1808 fleeing from Napoleon's invasion had nothing to do with the proud Court that concerned Britain in 1816 for its expansionist aspirations. Much water had flowed under the bridges and other winds blowing in Europe and America. The endless possibilities of large and rich country of Brazil, economic development produced by the opening of Brazilian ports to international trade-decision of 1808 - and remoteness from European conflicts resulted in a bold idea of the Portuguese political leadership. Convert Brazil to the center of decision and permanent seat of the Kingdom and its authorities. The presence of the Portuguese government in America has substantially changed the geopolitical vision of its leaders. This idea was seriously considered by the King, particularly after the death of his mother, Queen Maria, which occurred in March 1816, who was mentally inhibited from long ago. The Prince Regent finally ascended the throne under the name of
John VI. The flamboyant monarch gave his decidedly biased American policy. Brazil seemed to assure the Braganza a first order global destination, which the little Portugal would no longer offer. A decree almost immediately transformed the Kingdom of Portugal in the United Kingdom of Portugal, Brazil and the Algarves, Brazil was no longer a colony and passed to form the Kingdom of Brazil, an essential part of the Portuguese state. From that moment the expansionist policy was accentuated and the idea of an Empire of Brazil was encouraged and supported. Such a policy did not coincide with the plans of Britain, and was opposed by
Lord Strangford, the British ambassador to Portugal who previously had a strong influence on the Portuguese government. The dispute culminated when John VI himself called on London, in April 1815, to replace Lord Strangford, which was done almost immediately. These circumstances did not alter the old dependency of Portugal, and then of Imperial Brazil, on the British. But the end of Lord Strangford's tenure as ambassador allowed John VI to execute his old plan to invade and annex the Banda Oriental. Particular interest in the project, had the planters of
Rio Grande do Sul, which on the one hand, aspired to control the overseas port of Montevideo as a way to channel their business (the strong regional and even separatist tendencies in the region had the highest interest in having its own exit that would link to international trade), and on the other hand, were concerned about the implementation of rural artiguista regulation, adopted in September 1815, which established the right of confiscation of the lands of the enemies of the revolution with its disrespect for property rights and the phenomenon of rural populace dividing the land, under the banner "The most unhappy are the most privileged". In addition, under the chaos prevailing in the United Provinces, which declared independence after the Congress of Tucumán, and the "radicalism" of Artigas, he regarded the Banda Oriental as a dangerous center spread of "anarchy" to impulses of the "Montoneros" federalist and republican. No wonder then that the Marquis of Alegrete riograndense warlord, has made maximum efforts for the project, and that those who were later prominent leaders of separatism riograndense, Bento Gonçalves da Silva and Bentos Manuel Ribeiro, have played with it a leading role. Also, Spanish and American emigrants who sought refuge in Brazil persuaded the Portuguese and Brazilian King John VI, to initiate a military campaign on the Banda Oriental.
Gaspar de Vigodet, last Spanish colonial governor of Montevideo and the Spanish friar Cirilo Alameda promoted the adventure with the hope that, once obtained the victory, Portugal would return those territories to Spanish rule. The locals unit exiled by the Fontezuelas Mutiny led by Carlos de Alvear, expected a defeat of Artigas, leader of federalism, and supplied the Portuguese-Brazilian Court with any information, to support their plans. Anti-artiguist orientals (Mateo Magariños, José Batlle and Carreó) also made an important effort in this regard. Particular importance was Nicolas Herrera, former secretary of the government of Alvear deposed in 1815. Herrera arrived in Rio de Janeiro in exile, disgraced and bankrupt, but his undeniable charm and talent enabled him to persuade Antonio de Araujo y Acevedo, Count da Barca, one of the chief advisers of John VI. Soon those responsible for Portuguese-Brazilian politics appreciated the knowledge of the lawyer in respect to geography and political reality of the province to annex.
Complicity of Buenos Aires The main drawback of the campaign of conquest lay in the possibility that the United Provinces of the Río de la Plata react in defense of a territory which formed part of the country since its inception. Certainly it was not convenient to Portugal that the annexation of the Banda Oriental resulted in a difficult war, against all the provinces of La Plata. According to Uruguayan historians Washington Reyes Abadie, Oscar H. Bruschera and Tabaré Melogno, and the Argentine Raúl Scalabrini Ortiz, the information about Buenos Aires neutrality was first given by
Manuel José García, sent to negotiate with Britain and the court in Rio de Janeiro that they do not support the Spanish Empire, at a time when it was trying to recover the independent colonies. According to the Uruguayan writer Lincoln Maiztegui Casas, "Garcia with his ideal and interventional unit used all his influence to persuade the Portuguese King that the government of Buenos Aires would not take military action to keep the Oriental territory." Regarding the role of
Juan Martín de Pueyrredón, who took office in 1816 as Supreme Director of the United Provinces replacing Alvear, Maiztegui Casas asserts that although he differed from the radical Unitarianism of those who had commissioned Garcia, he thought that the unitarian party was not strong enough to subdue the federal movement, which quickly spread over the provinces; Pueyrredón, same as the previous rulers, was sympathetic to a defeat of Artigas, still considering him an expression of barbarism. Pueyrredón's attitude was ambiguous against the Portuguese invasion, accounting for one side that it implied in Buenos Aires the struggle against federalism and artiguismo in particular, but on the other hand also to a public in Buenos Aires that was strongly opposed to Portuguese control over the territory and the British desire to see the creation of a small independent state in the region. Ultimately, Pueyrredón as supreme director, collaborated with the invasion, not only because he did not declare war on the United Kingdom of Portugal, Brazil and the Algarves to the occupation of part of the country he governed, but because he steadily attacked the provinces of the Federal League, which were inhibited to cooperate with the defense of the territory organized by Artigas. But it also happened after of facts that can not be omitted, including the intransigence of the Protector, Artigas who systematically and firmly refused to recognize the authority of the Supreme Director of the
United Provinces of Rio de la Plata, which led him to the conviction that Artigas was intratable. Pueyrredón, expressing a political line that held differences with predominantly Unity Party in Buenos Aires since 1812, and was taken with considerable concern the Portuguese invasion of the Banda Oriental, with no objective reasons to ensure that such attitude was apparent. First, Nicolas de Vedia sent to interview Lecor, leading a trade to ensure that the invasion did not continue to Entre Rios, but that he had instructions to "keep on Buenos Aires strict neutrality". The commissioner returned to Buenos Aires a letter of assurance that would not pass the Portuguese adventure in the Oriental Province, obtained in conversation with Nicolas Herrera. Then Pueyrredón sent some weapons and war supplies to Artigas (low volume, but as a testimony of good will; 300 frames and 100 pounds of gunpowder), issued a loan of 200,000 pesos for military spending and war, a committee responsible for organizing the potential conflict. ==Military planification==