Ernest I, Duke of Saxe-Gotha (1601–1675) had married Elisabeth Sophie, the only child of Johann Philipp, Duke of Saxe-Altenburg and Gotha (1597–1638), the eldest son of Frederick William I. When Elisabeth Sophie's cousin Frederick William III, Duke of Altenburg, died unmarried 1672, the entire first Altenburg line became extinct in male line, opening a succession strife.
Frederick, Duke of Saxe-Altenburg (= 20) 12. Georg, Duke of Saxe-Altenburg: 25. Duchess Charlotte Georgine of Mecklenburg-Strelitz (= 21) 6. Prince Moritz of Saxe-Altenburg: 26. Frederick Louis, Hereditary Grand Duke of Mecklenburg-Schwerin: 13. Duchess Marie Louise of Mecklenburg-Schwerin: 27. Grand Duchess Elena Pavlovna of Russia: 3.
September 22, 1875 – Birth of Adelheid of Schaumburg-Lippe, Duchess of Saxe-Altenburg, wife of Ernst II, Duke of Saxe-Altenburg at Ratibořice Castle in Bohemia, now in the Czech Republic Full name: Friederike Adelheid Marie Luise Hilda Eugenie In 1898, Adelheid married the future Ernst II, Duke of Saxe-Altenburg and the couple had four children.
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