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.
Altenburg and a few other districts were added to the Ernestine possessions by the treaty of Naumburg in 1554, and other additions were made from other sources.
John, duke of Saxe-Weimar, who died in 1605, is regarded as the common ancestor of the present Ernestine lines.
Augustus supported his brother during the war of the league of Schmalkalden, and in the policy which culminated in the transfer of the Saxon electorate from John Frederick I., the head of the Ernestine branch of the Wettin family, to Maurice.
The Saxe-Weimar family is the oldest branch of the Ernestine line, and hence of the whole Saxon house.
In the 14th century it passed to the elector of Saxony, falling at the partition of 1485 to the Ernestine branch of the Wettin family.
Since 1485 it has remained in the Ernestine line of the house of Saxony.
On the extinction of that line Gotha came into the possession of the electors of Saxony, and it fell later to the Ernestine line of dukes.
He was thus the last Ernestine elector of Saxony.
The principality of Eisenach fell to the Saxon house of Wettin in 1440, and in the partition of 1485 formed part of the territories given to the Ernestine line.