Question: What is the date of birth of Gertrude Von Hanau's husband?
Sentence (from "Frederick William, Elector of Hesse"): Frederick William I (20 August 1802 – 6 January 1875) was, between 1847 and 1866, the last Prince-elector of Hesse-Kassel (or Hesse-Cassel).
Relevant evidence: Yes