6 Groschens – Polish–Lithuanian Commonwealth

By 1660, the Polish–Lithuanian Commonwealth was in the throes of a severe monetary crisis, often termed the "Potop" or "Deluge," which had devastated its economy. The Commonwealth's currency, based on a bimetallic system of silver złoty and copper shillings (solidi), was fundamentally destabilized. A primary cause was the massive, unauthorized minting of copper shillings by Swedish occupiers and the Lithuanian Treasurer, Tytus Liwiusz Boratini, during the Swedish invasion (1655-1660). These debased coins, known as boratynki, flooded the market, causing rampant inflation and a collapse in public trust, as their face value far exceeded their intrinsic metal worth.

This currency chaos was exacerbated by the wider devastation of the Deluge, which saw population loss, agricultural ruin, and the looting of state treasuries and royal mints. The state's ability to control its monetary policy was crippled, leading to a classic "bad money drives out good" scenario (Gresham's Law). Holders of full-weight silver coins hoarded or exported them, leaving only the depreciating copper currency in common circulation. This hyperinflation severely disrupted trade, tax revenues, and military financing at a time when the Commonwealth was still engaged in costly wars with Russia and recovering from conflict with Sweden.

In response, King John II Casimir Vasa and the Sejm attempted monetary reform. The crucial legislation came with the Currency Act of 1660, which aimed to restore confidence by demonetizing the debased copper coinage and returning to a stable silver-based system. The reform set a fixed exchange rate between new silver coins and the old copper ones, but the process was painful and only partially successful. It required significant state expenditure to redeem the copper coins, placing a further burden on an exhausted treasury, and the economic scars of the crisis would linger for decades, highlighting the profound link between political stability and monetary integrity.