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
According to those historians, the Spanish revolution against absolutism got mixed up with the Peninsular War. When Ferdinand VII stood against his father Charles IV, who was seen as an absolutist king, many Spaniards got the mistaken impression that he sympathized with the new enlightened ideas. Thus, the revolutions made in the Americas in the name of Ferdinand VII (such as the May Revolution, the Chuquisaca Revolution, or the one in Chile) would have sought to replace absolutist power with power formulated under the new ideas. Even if Spain was at war with France, the ideals of the French Revolution (liberty, equality and fraternity) were still respected. Those revolutions pronounced themselves enemies of Napoleon, but did not face any active French military attack; they promoted instead fights between Spanish armies for keeping either the old or new order. This situation would change with the final defeat of Napoleon and the return of Ferdinand VII to the throne, as he began the Absolutist Restoration and persecuted the supporters of the new libertarian ideas within Spain. For people in South America, to stay as a part of the Spanish Empire, but with a new relationship with the mother country, was no longer a feasible option: the only remaining options at this point were to return to absolutism or to adopt independentism.