1 Ducat - John Frederick

John Frederick, who ruled Calenberg from 1665 until his death in 1679, was a Catholic convert governing a predominantly Lutheran territory — a tension he managed largely by leaving confessional affairs undisturbed while pursuing an aggressively ambitious foreign policy. He aligned Brunswick-Calenberg with France during Louis XIV's Dutch War, a gamble that brought French subsidies and military prestige but left his successors deeply entangled in continental power struggles.

The Fr#569 attribution places this squarely within a ducat series that saw irregular output; Calenberg's mint at Hannover was never among the high-volume operations of the German states.