The district of Coburg came into the possession of the family of Wettin in the 14th century, and after the Wettins had become electors of Saxony this part of their lands fell at the partition of 1485 to the Ernestine branch of the house.
At the partition of Saxony in 1485 Weimar, with Thuringia, fell to the elder, Ernestine, branch of the Saxon house of Wettin, and has been the continuous residence of the senior branch of the dukes of this line since 1572.
The last decade of his life was made cheerful by his marriage with Ernestine Muller, who shared all his interests and learned Greek to help him with collations.
The crown is hereditary in the Albertine line of the house of Wettin, with reversion to the Ernestine line, of which the duke of Saxe-Weimar is now the head.
Only a few scattered territories were reserved for John Frederick's sons, although these were increased by the treaty of Naumburg in 1554, and on them were founded the Ernestine duchies of Saxe-Gotha, Saxe-Weimar, Saxe-Coburg, Saxe-Meiningen and Saxe-Altenburg.