Saxe-Coburg-Eisenach
The two princes at this time were still children, so the Elector August of Saxony was regent until 1586.  This is when Johann Casimir and Johann Ernst becgan to rule the duchy.  Johann Ernst retired to his hunting lodge in Marksühl, and in 1590 the two brothers divided the country. Johann Casimir  kept Saxe-Coburg, and Johann Ernst took Saxe-Eisenach. Johann Casimir died in 1633so his brother Johann Ernst inherited his possessions, again were short and Coburg and Eisenach were reunited until Johann Ernst's death in 1638.