5 Centavos

Banco Mauá & Ca. was the Argentine arm of the financial empire built by Irineu Evangelista de Sousa — Baron Mauá — the Brazilian industrialist whose banking network stretched across the Río de la Plata region in the 1850s and 1860s. The Rosario branch operated during a period when provincial and private banks in Argentina routinely issued their own fractional notes to compensate for the chronic scarcity of small coin.

1865 is the year the Paraguayan War began, and the resulting monetary disruptions across the region almost certainly accelerated demand for exactly this kind of low-denomination private paper. Mauá's broader financial house collapsed in 1875, which puts a hard outer limit on the active life of anything bearing his institutions' name.