Baltasar Hidalgo de Cisneros in the context of Juan José Castelli

The May Revolution (Spanish: Revolución de Mayo) was a week-long series of events that took place from 18 to 25 May 1810, in Buenos Aires, capital of the Viceroyalty of the Río de la Plata. This Spanish colony included roughly the territories of present-day Argentina, Bolivia, Paraguay, Uruguay, and parts of Brazil. The result was the removal of Viceroy Baltasar Hidalgo de Cisneros and the establishment of a local government, the Primera Junta (First Junta), on 25 May.

The May Revolution was a direct reaction to Napoleon's invasion of Spain. In 1808, King Ferdinand VII abdicated in favour 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 1 February 1810, French troops took Seville and gained control of most of Andalusia. The Supreme Junta retreated to Cádiz, formed the Council of Regency of Spain and the Indies to govern, and dissolved itself. News of these events arrived in Buenos Aires on 18 May, brought by British ships.

Manuel José Joaquín del Corazón de Jesús Belgrano (3 June 1770 – 20 June 1820), usually referred to as Manuel Belgrano (Spanish pronunciation: [maˈnwel βelˈɣɾano]), was an Argentine public servant, economist, lawyer, politician, journalist, and military leader. He took part in the Argentine Wars of Independence and designed what became the flag of Argentina. Argentines regard him as one of the main Founding Fathers of the country. He was also a supporter of free trade.

Belgrano was born in Buenos Aires, the fourth child of Italian businessman Domingo Belgrano y Peri and of María Josefa González Casero. He came into contact with the ideas of the Age of Enlightenment while at university in Spain around the time of the 1789 French Revolution. In 1794 he returned to the Viceroyalty of the Río de la Plata, where he became a notable member of the criollo population of Buenos Aires; he tried to promote some of the new political and economic ideals, but found severe resistance from local peninsulares. This rejection led him to work towards a greater autonomy for his country from the Spanish colonial regime. At first he unsuccessfully promoted the aspirations of Carlota Joaquina to become a regent ruler for the Viceroyalty during the period when the French imprisoned the Spanish King Ferdinand VII during the Peninsular War (1807–1814). Belgrano favoured the May Revolution, which removed the viceroy Baltasar Hidalgo de Cisneros from power on 25 May 1810. He was elected as a voting member of the Primera Junta that took power after the ouster.