Frederick IV, Duke of Saxe-Gotha-Altenburg
Frederick IV, Duke of Saxe-Gotha-Altenburg (Gotha, 28 November 1774 – Gotha, 11 February 1825), was the last duke of Saxe-Gotha-Altenburg.
He was the third but second surviving son of Ernst II, Duke of Saxe-Gotha-Altenburg and Charlotte de Saxe-Meiningen.
After the death of his older brother August without sons (1822), Frederick (the only surviving male of the house) inherited the duchy of Saxe-Gotha-Altenburg.
Frederick fought - after military training - in the Napoleonic campaigns and was heavily wounded.
As a consequence of these injuries, he was constantly ill until his death.
Because of his illness, he traveled for a long time seeking a cure.
During these stays outside of his duchy, he left the government in hands of his secret advisor Bernhard August von Lindenau.
He only reigned three years and died unmarried; with him, the line of Saxe-Gotha-Altenburg ended.
After his death, his lands were repartitioned among his Wettin relations.
Ernst I of Saxe-Coburg-Saalfeld received Gotha, and changed his title to "Duke of Saxe-Coburg and Gotha", although the two duchies remained technically separate in a personal union.
Altenburg was thereafter ruled by the Duke of Saxe-Hildburghausen, whose dukedom was transferred to Saxe-Meiningen along with Saxe-Saalfeld, which Saxe-Coburg gave up in return for receiving Saxe-Gotha.
Anna Sophie of Saxe-Gotha-Altenburg
Duchess Anna Sophie of Saxe- Gotha-Altenburg( 22 December 1670 – 28 December 1728) was a princess of Saxe- Gotha- Altenburg and Duchess in Saxony by birth, and by marriage a Princess of Schwarzburg- Rudolstadt.
Ernest II, Duke of Saxe-Gotha-Altenburg
Ernest II, Duke of Saxe-Gotha-Altenburg (Gotha, 30 January 1745 – Gotha, 20 April 1804) was the reigning Duke of Saxe-Gotha-Altenburg from 1772 to 1804.
He was the third but second surviving son of Frederick III, Duke of Saxe-Gotha-Altenburg and Luise Dorothea of Saxe-Meiningen.
The death of his older brother Frederick in 1756 made him the heir to the duchy of Saxe-Gotha-Altenburg.
Prince John August of Saxe-Gotha-Altenburg
Johann August of Saxe- Gotha-Altenburg( 17 February 1704 – 8 May 1767), was a German prince, member of the House of Saxe- Gotha- Altenburg.
He was born in Gotha, the fifth but second surviving son of Frederick II, Duke of Saxe- Gotha- Altenburg and Magdalene Augusta of Anhalt- Zerbst.
Princess Charlotte of Saxe-Meiningen
Princess Charlotte of Saxe- Meiningen( 11 September 1751, Frankfurt am Main, Free Imperial City of Frankfurt, Holy Roman Empire – 25 April 1827, Genoa, Kingdom of Sardinia) was a member of the House of Saxe- Meiningen and a Princess of Saxe- Meiningen by birth and a member of the House of Saxe- Gotha- Altenburg and Duchess consort of Saxe- Gotha- Altenburg through her marriage to Ernest II, Duke of Saxe- Gotha- Altenburg.
Dorothea Maria of Saxe-Gotha-Altenburg
Dorothea Maria of Saxe-Gotha-Altenburg (12 February 1654 in Gotha – 17 June 1682 in Gotha), was a German princess member of the House of Wettin in the Ernestine branch of Saxe-Gotha-Altenburg.
She was the twelfth child and fourth daughter of Ernest I, Duke of Saxe-Gotha by his wife Elisabeth Sophie, the only daughter of John Philip, Duke of Saxe-Altenburg.
Ernest I, Duke of Saxe-Gotha
Ernest I, called "Ernest the Pious" (25 December 1601 – 26 March 1675), was a duke of Saxe-Gotha and Saxe-Altenburg.
The duchies were later merged into Saxe-Gotha-Altenburg.
He was the ninth but sixth surviving son of Johann II, Duke of Saxe-Weimar, and Dorothea Maria of Anhalt.
His mother was a granddaughter of Christoph, Duke of Württemberg, and great-granddaughter of Ulrich, Duke of Württemberg.
Johann Adolf of Saxe-Gotha-Altenburg
Johann Adolf of Saxe- Gotha-Altenburg( 18 May 1721, Gotha – 29 April 1799, Friedrichstanneck, now a district of Eisenberg, Thuringia), was a German prince of the House of Saxe- Gotha- Altenburg and a Saxon lieutenant general.
Dorothea Marie of Saxe-Gotha-Altenburg
Dorothea Marie of Saxe- Gotha-Altenburg( 22 January 1674 – 18 April 1713) was the wife of Ernst Ludwig I, Duke of Saxe- Meiningen.
She was the daughter of Frederick I, Duke of Saxe- Gotha- Altenburg and his first wife, Magdalena Sybille of Saxe- Weissenfels.
She married Ernst Ludwig I on the 19 September 1704.
Frederick III, Duke of Saxe-Gotha-Altenburg
Frederick III, Duke of Saxe- Gotha-Altenburg( 14 April 1699 – 10 March 1772), was a duke of Saxe- Gotha- Altenburg.

Question: When did Dorothea Maria Of Saxe-Gotha-Altenburg's father die?