The first rulers of Rethel might have governed under the Abbey of Saint-Remi and later independently, before the county passed first to the counts of Nevers, then to the counts of Flanders, and finally to the dukes of Burgundy. In 1405 the county became part of the peerage of France, and in 1581 it was elevated to a duchy. In 1663 it became the Duchy of Mazarin.
The county was active in the crusades. King Baldwin II of Jerusalem was the brother of Count Gervais and Countess Matilda of Rethel, while Beatrice of Rethel married Leo I, Prince of Armenia.