May Revolution
The mutiny of Aranjuez in 1808 led King Charles IV of Spain to abdicate in favor of his son, Ferdinand VII. Charles IV requested that Napoleon restore him to the throne; instead, Napoleon crowned his own brother, Joseph Bonaparte, as the new Spanish King. These events are known as the Abdications of Bayonne. Joseph's coronation was met with severe resistance in Spain, which started the Peninsular War, and the Supreme Central Junta took power in the name of the absent king. This also led to Spain switching allegiances from France to Britain. France eventually invaded Sevilla, and a Council of Regency based in Cadiz replaced the disbanded Supreme Central Junta.
First National Government
Commemorations of the May Revolution have been held since 1811, the first anniversary: Cornelio Saavedra ruled so for Buenos Aires, and Manuel Belgrano and Juan José Castelli did the same during their military campaigns at the cities they had under control during the anniversaries. The day was officially declared a national day by the Assembly of Year XIII on May 5, 1813. The 1816 Argentine Declaration of Independence provided an alternative national day. In the beginning, this added to the conflicts between Buenos Aires and the provinces in the Argentine Civil War, with the date in May being related particularly to Buenos Aires and 9 July to the whole country. This led the unitarian Bernardino Rivadavia to cancel the celebration on July, and the federalist Juan Manuel de Rosas to re-allow it, but without giving up celebrations on May. The celebrations in 1857, when Buenos Aires had temporary seceded from the Argentine Confederation, were large and included the remodelation of the Plaza. By 1880, with the federalization of Buenos Aires, the local connotations were removed and the May Revolution was considered the birth of the nation.