Viceroyalty of the Río de la Plata

The Viceroyalty of the Río de la Plata was the last and shortest-lived of Spain's American viceroyalties. Created in 1776 with its capital at Buenos Aires, it covered what are now Argentina, Uruguay, Paraguay and Bolivia, and it broke apart in the independence movements that began in 1810.

Spanish explorers reached the Río de la Plata, "river of silver", in 1516. Pedro de Mendoza founded Buenos Aires in 1536, but it was abandoned, and Asunción, in Paraguay, founded in 1537, became the centre of Spanish settlement. Juan de Garay refounded Buenos Aires in 1580. For two centuries the region was a remote part of the Viceroyalty of Peru. Spain required trade to pass through Lima and Panama, so Buenos Aires relied on smuggling, especially of silver from Potosí and of enslaved Africans. Jesuit missions, reducciones, among the Guaraní in Paraguay, organised Indigenous communities until the Jesuits were expelled in 1767.

Portugal founded Colonia do Sacramento in 1680, on the opposite shore of the Río de la Plata, as a base for smuggling, and Spain and Portugal fought over it repeatedly. Spain founded Montevideo in 1724 to counter Portuguese expansion.

In 1776, to defend the region against Portugal and Britain and to control the silver trade, Spain created the Viceroyalty of the Río de la Plata, with Buenos Aires as capital. It included Upper Peru, with Potosí, giving Buenos Aires control of the silver. The first viceroy, Pedro de Cevallos, took Colonia. In 1778 the Regulation of Free Trade allowed Buenos Aires to trade directly with Spain, and the city grew rapidly, its merchants exporting hides, silver and later salted beef. Cattle ranching on the pampas, worked by gauchos, became important.

In 1806, during the Napoleonic Wars, a British force under William Beresford took Buenos Aires; the viceroy, Rafael de Sobremonte, fled. Local militias, led by Santiago de Liniers, a French-born officer, retook the city. In 1807 a larger British force took Montevideo and attacked Buenos Aires, but was defeated in street fighting, with residents throwing boiling oil and stones from rooftops. The victory gave the people of Buenos Aires, especially the criollos, American-born Spaniards, confidence and an armed militia, and Liniers was named viceroy by popular demand.

In 1810, when news arrived that Napoleon's armies had taken most of Spain, the cabildo, town council, of Buenos Aires held an open meeting. On 25 May 1810 the viceroy, Baltasar Hidalgo de Cisneros, was replaced by a junta, the Primera Junta, led by Cornelio Saavedra, with Mariano Moreno and Manuel Belgrano. The date is a national holiday in Argentina.

The rest of the viceroyalty did not follow Buenos Aires. Paraguay defeated a Buenos Aires army under Belgrano and declared independence in 1811, later ruled by the dictator José Gaspar Rodríguez de Francia. Upper Peru remained in royalist hands until 1825, when it became Bolivia. The Banda Oriental, today's Uruguay, led by José Gervasio Artigas, fought Buenos Aires and was occupied by Portugal and Brazil, becoming independent as Uruguay in 1828 after a war between Brazil and Argentina. The United Provinces of the Río de la Plata declared independence at Tucumán on 9 July 1816.

Our maps show the viceroyalty on the 1783 and 1800 maps. Its outline, about 2.4 million square kilometres at most, is more than 90 percent in today's Argentina, with most of the rest in Uruguay; the basemap draws Bolivia and Paraguay separately. Buenos Aires lies inside it. On the 1815 map, the region appears as the United Provinces of the Río de la Plata.