The famous Plaza de Mayo in Buenos Aires is named in honor of these actions. The lands of the eastern southern cone of South America, including Argentina, Uruguay, Bolivia, and Paraguay, had been steadily growing in importance for the Spanish crown, mostly because of revenues from the lucrative ranching and leather industry in the Argentine pampas. In , this importance was recognized by the establishment of a Viceregal seat in Buenos Aires, the Viceroyalty of the River Platte.
This elevated Buenos Aires to the same status as Lima and Mexico City, although it was still much smaller. The wealth of the colony had made it a target for British expansion. The Spanish were correct: the British had their eye on Buenos Aires and the rich ranching land it served. In the British made a determined effort to capture the city. Spain, its resources drained from the devastating loss at the Battle of Trafalgar, was unable to send any help and the citizens of Buenos Aires were forced to fight off the British on their own.
This led many to question their loyalties to Spain: in their eyes, Spain took their taxes but did not hold up their end of the bargain when it came to defense. In , after helping France overrun Portugal, Spain was itself invaded by Napoleonic forces. Napoleon, wanting someone he could trust, put his brother Joseph on the throne in Spain. Spain desperately tried to keep news of this disaster from reaching its colonies. Since the American Revolution, Spain had kept a close eye on its own New World holdings, fearing that the spirit of independence would spread to its lands.
They believed that the colonies needed little excuse to cast off Spanish rule. Rumors of a French invasion had been circulating for some time, and several prominent citizens were calling for an independent council to run Buenos Aires while things got sorted out in Spain.
On May 13, , a British frigate arrived in Montevideo and confirmed the rumors: Spain had been overrun. Buenos Aires was in an uproar.
