5 Mil Réis Thesouro Nacional, 6th print

Brazil's Imperial Treasury turned to Perkins, Bacon & Petch for much of its mid-nineteenth-century paper currency production — the same London firm whose steel-engraved intaglio work had already become the global standard for secure banknote printing, used extensively by British colonial administrations and foreign governments unable to sustain domestic security printing. The "6th print" designation indicates this is one of several successive printings of the same basic plate design, a common arrangement when a colonial or imperial government contracted a fixed-plate run and then ordered replenishments as notes wore out or reserves depleted.

By 1866, Brazil was already eighteen months into financing the Paraguayan War — the most costly conflict in South American history — and pressure on the Imperial Treasury's note supply was significant.