Ernst Johann von Biron's restoration to the Courland duchy in 1763 — after over two decades of Siberian exile following his arrest on Anna of Russia's death — produced one of the more unusual political coinages in Baltic history. The grossus issues of 1763–64 represent his first opportunity to strike coins as a ruling duke since the 1730s, and were produced at Mitau under circumstances of considerable constitutional ambiguity, given Russian suzerainty over the duchy throughout this period.
Ernst Johann von Biron's restoration to the Courland duchy in 1763 — after over two decades of Siberian exile following his arrest on Anna of Russia's death — produced one of the more unusual political coinages in Baltic history. The grossus issues of 1763–64 represent his first opportunity to strike coins as a ruling duke since the 1730s, and were produced at Mitau under circumstances of considerable constitutional ambiguity, given Russian suzerainty over the duchy throughout this period.