In 1825 the ruler died, and he also had no male heirs. Saxe-Gotha-Altenburg was split up. Gotha was given to the Duke of Saxe-Coburg-Saalfeld and Altenburg to the Duke of Saxe-Hildburghausen, who in exchange gave up Saalfeld and Hildburghausen to the Duke of Saxe-Meiningen. This family ruled in the duchy until the end of the monarchies in 1918. Saxe-Altenburg became part of the new state of Thuringia in the Weimar Republic in 1920.