6 Kreuzer

Frankfurt struck this coin in the final months of its existence as an independent city-state. In July 1866, Prussian forces occupied Frankfurt following the Austro-Prussian War — the city had backed Austria — and by September it was annexed outright, its centuries-old autonomy extinguished by Bismarck's reorganization of German territories. Coins dated 1866 were almost certainly struck before the occupation, making them among the last issues of a mint that had operated under municipal authority since the medieval period.

The billon composition reflects the chronic small-change economics of mid-century German states, where fractional silver denominations were routinely debased to control costs.