Denier with quartered shield - John III

John III ruled Brittany for nearly four decades without producing a male heir, a dynastic failure that directly triggered the War of Breton Succession upon his death in 1341 — one of the most destructive conflicts of fourteenth-century France. His coinage therefore spans the entire lead-up to that catastrophe. The quartered shield design reflects his claim through both the Dreux line and the broader assertion of ducal independence from the French crown, a political posture John maintained carefully throughout his reign despite owing nominal homage to Philip VI.

Billon quality for Breton deniers of this period varies considerably across the issue's three-decade span, as ducal mints adjusted alloy composition in response to broader French monetary manipulations.