1 Solidus - Friedrich Casimir Kettler Mitau

Friedrich Casimir Kettler ruled Courland and Semigallia from 1682 until his death in 1698, and his later years were marked by severe financial strain and increasing Polish-Lithuanian suzerainty over the duchy. The 1696 solidus was struck at Mitau — the ducal capital, now Jelgava in Latvia — during a period when billon coinage of this denomination served primarily as small change in a territory caught between Swedish imperial ambitions and Polish overlordship. Friedrich Casimir died just two years after this piece was struck, leaving no legitimate heir, which triggered a succession crisis that eventually brought Ernst Johann Biron to power decades later.