1/2 Groat (półgrosz) - Sigismund II Augustus (2d eagle)

Sigismund II Augustus ruled the Grand Duchy of Lithuania as the last Jagiellonian monarch, and the półgrosz series issued under his name spans the entire arc of his reign — a period during which the Union of Lublin (1569) would ultimately dissolve the duchy's separate monetary identity into the Polish-Lithuanian Commonwealth. The sheer volume of Kopicki reference numbers here reflects not collector pedantry but genuine die proliferation: Vilnius mint workers churned through an enormous number of working dies across these decades, producing measurable variation in punch placement, die alignment, and legend spelling that specialists have been cataloguing since the 19th century.

The fineness reduction in 1558, from .375 to .344 silver, was deliberate policy — part of broader currency debasement tied to the financial pressures of the Livonian War, which began that same year.