Amid Napoleon's occupation of Spain and the collapse of royal authority, residents of Buenos Aires pressured Viceroy Baltasar Hidalgo de Cisneros to step down, replacing colonial rule with a self-governing junta. The event, celebrated as the May Revolution, is considered the foundational moment of Argentine independence, though full separation from Spain would not be declared until 1816.
News that Napoleon's armies had overrun Spain and dismantled its monarchy reached Buenos Aires in May 1810 and threw the colonial government into crisis. If there was no legitimate king in Spain, colonists argued, then sovereignty ought to revert to the people rather than rest with an unelected viceroy. A week of tense assemblies, known as the Cabildo Abierto, culminated on May 25 when crowds gathered outside the government house demanding the viceroy's resignation.
Viceroy Baltasar Hidalgo de Cisneros, isolated and without meaningful military support, agreed to step down. In his place, the city's leading citizens formed the Primera Junta, a governing council that would rule in the name of the deposed Spanish king Ferdinand VII while functioning as a de facto independent government.
The symbolism proved as important as the politics. Popular legend holds that the sun broke through overcast skies at the moment of the junta's formation, an image later commemorated on the Argentine flag as the 'Sun of May.' Though formal independence from Spain waited until 1816, Argentines mark May 25 as their revolutionary birthday, celebrated nationally as Día de la Revolución de Mayo.
Key people: Baltasar Hidalgo de Cisneros, Cornelio Saavedra