The May Revolution was a week-long series of revolutionary events that took place from May 18 to May 25, 1810, in Buenos Aires, capital of the Viceroyalty of the Río de la Plata, a colony of the Spanish Empire which included the present-day nations of Argentina, Bolivia, Paraguay and Uruguay. The consequences of these events were the ousting of Viceroy Baltasar Hidalgo de Cisneros and the establishment of a local government, the Primera Junta (First Junta) on May 25. These events are commemorated in Argentina as "May Week" (Spanish: Semana de Mayo).
The May Revolution was a direct reaction to developments in Spain during the previous two years. In 1808 the Spanish king, Ferdinand VII had been convinced to abdicate by Napoleon in his favor, who granted the throne to his brother, Joseph Bonaparte. A Supreme Central Junta had lead a resistance to Joseph's government and the French occupation of Spain, but eventually suffered a series of reversals resulting in the 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 in favor of a Regency Council of Spain and the Indies. News of this arrived in Buenos Aires in May 18 on British ships bringing newspapers from Spain and the rest of Europe.
Initially, Viceroy Cisneros tried to conceal the news in order to maintain the political status quo, but he was unsuccessful. With the news of the turn of events in Spain, a group of Criollo lawyers and military officials organized an open cabildo (an extraordinary meeting of notables of the city) on May 22 to decide the future of the Viceroyalty. At this meeting it was decided to deny recognition to the Council of Regency in Spain, to end Cisneros' mandate as Viceroy since the government that appointed him no longer existed, and to establish a junta to govern in his place. In order to maintain a sense of continuity, Cisneros himself was initially appointed as the President of the Junta. However, this caused a great deal of popular unrest since it ran counter to the reasons for which his mandate was ended, so Cisneros resigned under pressure on May 25. Subsequently, the newly formed Primera Junta invited the other cities of the Viceroyalty to send delegates to join the Buenos Aires Junta, but this resulted in the outbreak of war between the regions that accepted the outcome of the events at Buenos Aires, and those that did not.
The May Revolution is considered the starting point of the Argentine War of Independence, although no formal declaration of independence was issued at the time, and the Primera Junta continued to govern in the name of the deposed Spanish king. As similar events occurred in many other cities of the Spanish South America when news of the dissolution of the Spanish Supreme Junta arrived, the May Revolution is also considered as one of the starting points for the Spanish American wars of independence. Historians today debate whether the revolutionaries were truly loyal to Ferdinand VII, or whether the declaration of fidelity to the king was a necessary ruse to conceal the true objective of achieving independence from a population that was not ready yet to accept such a radical change. A formal Declaration of Independence was only issued at the Congress of Tucumán on July 9, 1816
