2 Vereinsthaler - Frederick William IV

The Vereinsthaler — the "Union thaler" — emerged from the Vienna Coinage Treaty of 1857, which unified the monetary systems of Austria and the German states on a common silver standard. Prussia adopted the new convention immediately, and the double Vereinsthaler was struck as a high-value coin meant to circulate across member states without exchange penalties. Frederick William IV was by 1858 in the grip of severe mental decline following a series of strokes; his brother Wilhelm served as regent from October of that year.

The two-year emission window reflects the king's death in January 1861 and the subsequent retooling for his successor's coinage.