Rethel
The County of Rethel was a lordship in the Ardennes, seated at Rethel. In 1337 Louis I held it alongside Flanders and Nevers.
Louis was killed at Crécy in 1346. Rethel became a French peerage in 1481 and a duchy in 1581. In 1659 its last Gonzaga duke sold it to Cardinal Mazarin; renamed the Duchy of Mazarin, it survived until the French Revolution of 1789.