What historical event does the Sun of May on Uruguay's flag commemorate?

The Sun of May on Uruguay’s flag commemorates the May Revolution of 1810. That uprising in Buenos Aires began the independence process in the Viceroyalty of the Río de la Plata, the colonial region that included the territory of present-day Uruguay.

The emblem is a golden sun with a human face and 16 alternating straight and wavy rays. Uruguay adopted it as part of its national symbolism in 1828, soon after independence was established at the end of the Cisplatine War between the United Provinces of the Río de la Plata and Brazil.

The Sun of May also appears on Argentina’s flag and coat of arms, reflecting the shared historical traditions of the Río de la Plata region. It is often linked to Inti, the Inca sun god, although historians note that firm contemporary evidence for a specifically Inca origin is limited.

Uruguay’s flag originally had more stripes than it does today. The first 1828 design used 19 alternating stripes; a 1830 law reduced them to nine, representing the country’s original nine departments.