 In 1586, after the wedding of his brother with Anna of Saxony, the daughter of the Elector Augustus, the guardianship finalized, and Johann Casimir began, together with his brother, the independent ruling of Saxe-Coburg-Eisenach.Johann Casimir and Johann Ernst governed together the principality for the next ten years; however, Johann Casimir carried the main responsibility for the government as an older brother.Also, in order to had a separated residence from his brother too, Johann Ernst establishes himself in the small town of Marksuhl on 1587.