Duke of Saxe-Eisenach and the fifth but third surviving son of Wilhelm, Duke of Saxe-Weimar and Eleonore Dorothea of Anhalt-Dessau.
After the death of his father (1662), his older brother Johann Ernst II inherited Weimar, and his second brother Adolf Wilhelm received Eisenach. Johann Georg received an income from the new duchy of Saxe-Eisenach and took his residence in the small town of Marksuhl.
In 1668 his brother Adolf Wilhelm died. His fifth and only surviving son, Wilhelm August, was born eight days after his father’s death and became duke from the moment of his birth; Johann George became the regent of the duchy and also the guardian of the new duke. Wilhelm August died in 1671 at only two years of age, and Johann Georg inherited the duchy.
The next year (1672) the death without heirs of the Duke Frederick Wilhelm III of Saxe-Altenburg forced a new treaty of division of the family lands between Johann Georg, his surviving brothers and his cousin. Johann Georg was confirmed in his possession of Eisenach and took some towns, and his younger brother, Bernhard, inherited Jena.
Johann Georg thus became the founder of the most recent line of the dukes of Saxe-Eisenach, who became extinct in 1741. He was ruler in 1685 when Johann Sebastian Bach was born in the duchy.
In Wallau on 29 May 1661, Johann Georg married the Countess Johannetta of Sayn-Wittgenstein, heiress of Sayn-Altenkirchen. They had eight children.
He died on 19 September 1686, aged 52, in Eckhartshausen, Marksuhl.
Link to Wikipedia biography