Duchy of Saxe-Altenburg
From 1638 to 1672, Coburg and the fortress were part of the Duchy of Saxe-Altenburg. In 1672, they passed to the Dukes of Saxe-Gotha and in 1735 it was joined to the Duchy of Saxe-Saalfeld. Following the introduction of Primogeniture by Duke Franz Josias (1697-1764), Coburg went by way of Ernst Friedrich (1724-1800) to Franz (1750-1806), noted art collector, and to Duke Ernst III (1784-1844), who remodeled the castle.