In
Altenburg on 24 October 1636, the 17-year-old Elisabeth Sophie married her 34-year-old kinsman
Ernst I, Duke of Saxe-Gotha. As a
dower, she received 20,000
guilders, which were pledged by the town of
Roßla. As a widow's seat, the adolescent bride obtained the towns of
Kapellendorf and
Berka, with the latter called
Gartenhaus in
Weimar. Elisabeth Sophie was constantly pregnant for much of her marriage, giving birth almost once a year, but half of her children went on to die in childhood or adolescence; three of them died within weeks of each other in December 1657 due to a
smallpox outbreak. Due to the succession laws of the House of Saxe-Altenburg (which excluded women from inheritance), her father was succeeded by his brother,
Frederick William II, after he died a year and a half later on 1 April 1639. When her cousin, the duke
Frederick William III, died childless in 1672, Elisabeth Sophie became in the general heiress of the whole branch of Saxe-Altenburg on the basis of her father's testament (as it was ultimately recognized in law that the
Salic law did not prevent an
agnate from willing all his possessions to those other agnates of the house he desired to make his heirs, leaving other agnates without; and if those favored agnates also happened to be the testator's son-in-law and maternal grandsons, that was in no way prohibited). Ernest I of Saxe-Gotha claimed the whole succession of Saxe-Altenburg on the basis of both being the closest male relative and his wife's rights. However, the other branch of the family, the Dukes of
Saxe-Weimar, did not accept that will, opening a succession dispute. Finally, Elisabeth Sophie and Ernst's sons received most of the Saxe-Altenburg inheritance, but a portion (a quarter of the original duchy of Saxe-Altenburg) passed to the Saxe-Weimar branch. Hence, the Ernestine line of
Saxe-Gotha-Altenburg was founded, which would exist until 1825. When Duke Ernest I died in 1675, his numerous sons divided the inheritance (five eighths of all Ernestine lands) into seven parts:
Gotha-Altenburg,
Coburg,
Meiningen,
Römhild,
Eisenberg,
Hildburghausen and
Saalfeld. Of them, Coburg, Römhild and Eisenberg did not survive over that one generation and were divided between the four remaining lines. Of the four remaining duchies, only two branches survived until today: Meiningen and Saalfeld (which eventually became the house of
Saxe-Coburg-Gotha). Through the Saalfeld branch, Elisabeth Sophie was a direct ancestress of the
English royal family. After her husband's death, Elisabeth Sophie exchanged the towns originally given to her as widow's seat in her marriage contract for the towns of
Reinhardsbrunn and
Tenneberg. Under the name "
the Chaste", she became a member of the Virtuous Society. She died in
Gotha, aged 61. ==Issue==