Portuguese invasion of the Banda Oriental (1811–12)

Portuguese invasion of the Banda Oriental
The countryside of the Banda Oriental (Eastern Bank)
Date 23 July 1811–1812 Location Banda Oriental (present-day Uruguay) Result Inconclusive
Belligerents
Portuguese Empire Viceroyalty of the Río de la Plata	United Provinces of the Río de la Plata
Commanders and leaders
João (Prince Regent) Diogo de Sousa Joaquim Xavier Curado Manuel Marques de Sousa Francisco Javier de Elío	José Rondeau José Gervasio Artigas

The Portuguese invasion of the Banda Oriental was a short-lived and failed attempt, beginning in 1811 and ending the following year, by the Portuguese Empire to annex the remaining territory of the Spanish Viceroyalty of the Río de la Plata.

Portugal had long desired to secure the east bank of the River Plate (Río de la Plata) in South America, which it regarded the natural border of Brazil (the Portuguese Overseas Empire's largest and wealthiest colony). In 1680, the Portuguese founded the Colônia do Santíssimo Sacramento (Colony of the most Saintly Sacrament), the first European settlement on the river's eastern bank. It served mainly as a port for smuggling activities between Buenos Aires, which was already one of Hispanic America's major trading centers, and Brazil. Although Sacramento was only a few hours by ship from Spanish Buenos Aires, it was an outpost that was very isolated from Portugal's other possessions, requiring a two weeks sea voyage to reach the colony's capital at Rio de Janeiro. The need for defenses and development to shore up the southern flank was only slowly addressed, however, and the town's population never grew beyond 3,000 under Portuguese rule.

Spain did not lightly dismiss the construction of a settlement on territory it regarded as part of its colonial empire. The Spanish in Buenos Aires protested and demanded the withdrawal of the Portuguese outpost, claiming the entire area as theirs according to the Treaty of Tordesillas, signed centuries before in 1494. The Portuguese refused to comply, citing the same treaty as granting the east bank of the River Plate to them. In fact, the treaty had not assigned the east bank of the river to Portugal; the misconception was a result of a calculation error in determining the location of the demarcation line. Barely a few months after its foundation, Sacramento was captured by the Spanish, but was later returned to the Portuguese early in 1683. In 1704, during the War of the Spanish Succession, the Spanish forces again attacked and overran the Portuguese outpost. It was restored to Portugal only in 1716, after the Treaty of Utrecht was signed.

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