German duke, as the ninth but sixth surviving son of Ernst I, Duke of Saxe-Gotha and Elisabeth Sophie of Saxe-Altenburg.
When his father died in 1675, Ernst and his six brothers jointly assumed the government of the duchy; five years later, in 1680, and under the treaty of division of the family lands, he received the towns of Hildburghausen, Eisfeld, Heldburg, Königsberg. Ernst became thereby founder and first duke of Saxe-Hildburghausen. After the death of his brothers Heinrich and Albrecht without male descendants, he took the towns of Sonnefeld and Behringen.
Ernst settled his official residence in Hildburghausen and began the building of his castle. In 1710 he approved the building in his lands of a new city of French Huguenot families, who were driven out after the Edict of Nantes from France.
As Master of Cavalry he fought in 1683 in the Battle of Vienna, and 1685 in the conquest of Gran and Neuhaeusel, after this he entered the Dutch States Army as a Colonel with the conquest of Kaiserswerth.
In the building of his new residence, Ernst acquired a serious indebtedness of the principality to his brothers, which could not be reduced even by ever larger taxations.
He was married in Arolsen on the 30 November 1680 to Sophie of Waldeck. They had five children.
He died on 17 October 1715, aged 60, in Hildburghausen.
Link to Wikipedia biography