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
Juan José Castelli was the main speaker for the revolutionaries. He based his speech on two key ideas: the government's lapsed legitimacy—he stated that the Supreme Central Junta was dissolved and had no rights to designate a Regency—and the principle of retroversion of sovereignty. He spoke after Riega, and replied that the American people should assume control of their government until Ferdinand VII could return to the throne.