20 Pesos Fuertes

The Banco de la Província de Buenos Aires occupied an unusual position in Argentine monetary history: it functioned as a quasi-central bank for the province long before any national institution existed, and its notes circulated under a convertibility regime that was repeatedly suspended during fiscal emergencies. The 1865 issue coincided directly with the outbreak of the War of the Triple Alliance, when Buenos Aires was financing its share of a conflict that would drag on until 1870 and ultimately cost Paraguay the majority of its male population.

Wartime spending pressure made convertibility promises difficult to honor. Notes from this period are frequently found with heavy circulation wear — the pesos fuertes denomination itself was already a political statement, distinguishing "hard" peso obligations from the depreciated monedas corrientes that had plagued the region for decades.