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.
May Revolution
The revolution of May 1810 in Buenos Aires, intended to win the independence of Argentina from Spain, also had the consequence of emancipating the province of Buenos Aires from Argentina or, rather, of imposing the authority of this province upon the whole nation emancipated from Spain. That day, Spanish power over the Argentine provinces ended and that of Buenos Aires was established.