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.
2012 May Day protests
The first May Day protests originated in several countries throughout Europe including Stockholm, Madrid, London, Brussels, and Geneva in 1890. While the demand for an 8-hour workday was the primary concern that protesters were protesting for, other demands included improved working conditions, universal suffrage, peace among nations, and international solidarity. While it originally started as a labor movement in protest for improved wages and working conditions, protesters - who are primarily from working class backgrounds - now demonstrate for celebratory purposes and tradition while many others do it to create change.