4 Mariengroschen - John Frederick

John Frederick ruled Calenberg from 1665 until his death in 1679, a tenure defined largely by his conversion to Catholicism in 1651 — an extraordinary act for a Lutheran prince of the Holy Roman Empire that alienated much of his nobility and created persistent friction with the Estates throughout his reign. The 4 Mariengroschen denomination was a practical workhorse of Lower Saxon commerce, anchored to the Mariengroschen accounting system that had dominated regional trade since the fifteenth century.

Welter 1786 documents this type across a multi-year span, suggesting continuous demand rather than a single commemorative or administrative issue.