The May Revolution (Spanish: Revolución de Mayo) is a week-long series of events that takes place from May 18 to 25, 1810, in Buenos Aires, capital of the Viceroyalty of the Río de la Plata.

This Spanish colony includes roughly the territories of present-day Argentina, Bolivia, Paraguay, Uruguay, and parts of Brazil.

The result is the removal of Viceroy Baltasar Hidalgo de Cisneros and the establishment of a local government, the Primera Junta (First Junta), on May 25.

It is the first successful revolution in the South American Independence process.

The May Revolution is a direct reaction to Spain's Peninsular War.

In 1808, King Ferdinand VII of Spain had abdicated in favor of Napoleon, who had granted the throne to his brother, Joseph Bonaparte.

A Supreme Central Junta leads resistance to Joseph's government and the French occupation of Spain, but eventually suffers a series of reversals that resulted in the Spanish loss of the northern half of the country.

On February 1, 1810, French troops take Seville and gain control of most of Andalusia.

The Supreme Junta retreats to Cadiz and dissolves itself, and the Council of Regency of Spain and the Indies replaces it.

News of these events arrive in Buenos Aires on May 18, brought by British ships.

Viceroy Cisneros tries to maintain the political status quo, but a group of criollo lawyers and military officials organize an open cabildo (a special meeting of notables of the city) on May 22 to decide the future of the Viceroyalty.

Delegates deny recognition to the Council of Regency in Spain and establish a junta to govern in place of Cisneros, since the government that had appointed him Viceroy no longer exists.

To maintain a sense of continuity, Cisneros is initially appointed president of the Junta.

However, this causes much popular unrest, so he resigns under pressure on May 25.

The newly formed government, the Primera Junta, includes only representatives from Buenos Aires and invites other cities of the Viceroyalty to send delegates to join them.

This results in the outbreak of war between the regions that accept the outcome of the events at Buenos Aires and those that do not.

The May Revolution begins the Argentine War of Independence, although no formal declaration of independence os issued at this time and the Primera Junta continues to govern in the name of the deposed king, Ferdinand VII.

As similar events occur  in many other cities of the continent, the May Revolution is also considered one of the early events of the Spanish American wars of independence.

Historians today debate whether the revolutionaries were truly loyal to the Spanish crown or whether the declaration of fidelity to the king was a necessary ruse to conceal the true objective—to achieve independence—from a population that was not yet ready to accept such a radical change.

A formal declaration of independence will finally be issued at the Congress of Tucumán on July 9, 1816.