Question: What sovereign duke of the Duchy of Saxe-Coburg and Gotha, composed the opera Diana von Solange in 1858?
Sentence (from "List of heirs to Saxe-Coburg and Gotha"): The duchies of Saxe-Coburg and Saxe-Gotha remained in personal union until 1852, when a political union was effected.
Relevant evidence: No