Copyright: independence day (argentina)
July 9 is Día de la Independencia (Independence Day) in Argentina, commemorating the anniversary of the declaration of independence by the Congress of Tucumán, held in 1816 by the Spanish American provinces that later formed Argentina and Uruguay.
The Congress claimed the abdication of Spanish king Ferdinand VII to Napoleon of France, followed by the overthrow of the Spanish viceroy and establishment of the local government of the Primera Junta in 1810, had ended the control of Spain over its South American colonies. Spain's attempts to reassert control in 1814 caused the southern provinces to feel threatened to the point that, in 1816, they formed a General Congress to discuss independence, which was voted for on July 9, 1816.
More Information
Argentine Declaration of Independence (Wikipedia)