May Revolution
The May Revolution was a direct reaction to Spain's Peninsular War. In 1808, King Ferdinand VII of Spain abdicated in favor of Napoleon, who granted the throne to his brother, Joseph Bonaparte. A Supreme Central Junta led resistance to Joseph's government and the French occupation of Spain, but eventually suffered a series of reversals that resulted in the Spanish loss of the northern half of the country. On February 1, 1810, French troops took Seville and gained control of most of Andalusia. The Supreme Junta retreated to Cadiz and dissolved itself, and the Council of Regency of Spain and the Indies replaced it. News of these events arrived in Buenos Aires on May 18, brought by British ships.
Latin American wars of independence
Following the events of the May Revolution, in 1811 José Gervasio Artigas, led a successful revolt against the Spanish forces in the Provincia Oriental, now Uruguay, joining the independentist movement that was taking place in the Viceroyalty of the Río de la Plata at the time. In 1821, the Provincia Oriental was invaded by Portugal, trying to annex it into Brazil under the name of Província Cisplatina.