What was the capital of the union of provinces in the Río de la Plata comprised by most of the former dependencies from the last to be organized and also the shortest-lived of the Viceroyalties of the Spanish Empire in the Americas?
United Provinces of the Rio de la Plata The United Provinces of the Río de la Plata (Spanish: "Provincias Unidas del Río de la Plata" ), earlier known as the United Provinces of South America (Spanish: "Provincias Unidas de Sudamérica" ), a union of provinces in the Río de la Plata region of South America, emerged from the May Revolution in 1810 and the Argentine War of Independence of 1810–1818. It comprised most of the former Viceroyalty of the Río de la Plata dependencies and had Buenos Aires as its capital.
Real Audiencia of Charcas The Real Audiencia of Charcas (Spanish: "Audiencia y Cancillería Real de La Plata de los Charcas" ) was a Spanish "audiencia" with its seat in what is today Bolivia. It was established in 1559 in Ciudad de la Plata de Nuevo Toledo (later Charcas, today Sucre) and had jurisdiction over Charcas, Paraguay and the Governorate of the Río de la Plata, today Uruguay and northern Argentina. This court oversaw the incredible silver output of the mines at Potosí. It was part of the Viceroyalty of Peru until 1776, when it was transferred to the newly created Viceroyalty of the Río de la Plata and began to be referred to as Upper Peru.