Vem gifte sig med Magdalena Sibylla av Sachsen-Weissenfels?

Magdalena Sibylla av Sachsen-Weissenfels, född 2 september 1648 i Halle, död 7 januari 1681 i Gotha, var en tysk kunglighet.

Frederick I, Duke of Saxe-Gotha-Altenburg (15 July 1646 – 2 August 1691), was a duke of Saxe-Gotha-Altenburg. He was born in Gotha, the fourth but eldest surviving son of Ernst I, Duke of Saxe-Coburg-Altenburg and Elisabeth Sophie of Saxe-Altenburg.

When Ernst inherited the duchy of Saxe-Altenburg (1672), he made Frederick the regent of that duchy. In 1674 Ernst, who was already ill, made Frederick the regent of his entire lands.

After the death of his father (1675) Frederick assumed the throne of both duchies. However, on the basis of his family's house law, he had to allow his six younger brothers to take part in the government. At first, they agreed to a common household of all seven brothers in the Schloss Friedenstein, though this arrangement endured only until 1676.

Afterwards, negotiations began for the division of the paternal inheritance. This was finally accomplished on 24 February 1680; Frederick kept Gotha, Tenneberg, Wachsenburg, Ichtershausen, Georgenthal, Schwarzwald, Reinhardsbrunn, Volkenrode, Oberkranichfeld, Orlamünde, Altenburg and Tonna. These towns virtually formed the old duchy of Saxe-Gotha-Altenburg. They consisted of three large and coherent areas around Gotha, Kahla and Altenburg, as well as six smaller enclaves.

Frederick continued the work of his father. In order to prevent future disputes between his descendants, he established primogeniture for his house in 1685 (with Imperial assent granted in 1688). Around 1680 he established himself in the Lustschloss Friedrichswerth, near the village of Erffa, approximately 20 km of Gotha, which was renamed in his honour Friedrichswerth.

In 1683 Frederick created the (still in existence today) Theatre of Gotha (Gothaer Schloßtheater). He was also an eager diary writer; these diaries became one of the most important sources of his time. Frederick took part in the Great Turkish War against the Turks, and in the War of the Grand Alliance against France. He ruined the finances of his small duchy, however, using them to maintain a standing army, which by the time of his death counted over 10,000 men.