The duchy was established in 1640, when Duke
Wilhelm von Saxe-Weimar created a subdivision for his younger brother
Ernest I the Pious. Duke Ernest took his residence at
Gotha, where he had
Schloss Friedenstein built between 1643 and 1654. At the same time, the Duchy of
Saxe-Eisenach was created for the third brother
Albert IV. Nevertheless, Albert died in 1644, and Ernest inherited large parts of his duchy, though not the core territory around the residence at
Eisenach and the
Wartburg, which fell to his elder brother Wilhelm of Saxe-Weimar. Ernest could also incorporate several remaining estates of the extinct
House of Henneberg in 1660, which had been vacant since 1583. Finally in 1672 he received the major part of
Saxe-Altenburg through his wife
Elisabeth Sophie, after Altenburg's last duke
Frederick William III had died without heirs. Ernest would then be called Duke of
Saxe-Gotha-Altenburg. When Ernest died in 1675, he left his seven sons a significantly enlarged territory. The eldest,
Frederick I at first ruled jointly with his brothers until in 1680 the duchy was divided. The area around Gotha and also
Altenburg passed to Frederick I, who retained the title of a Duke of Saxe-Gotha-Altenburg. For later history of the duchy, see
Saxe-Gotha-Altenburg. == Dukes of Saxe-Gotha ==