Question: What is the date of death of Princess Mary Of Great Britain's husband?
Sentence (from "William I, Elector of Hesse"): William I, Elector of Hesse( 3 June 1743 – 27 February 1821) was the eldest surviving son of Frederick II, Landgrave of Hesse- Kassel( or Hesse- Cassel) and Princess Mary of Great Britain, the daughter of George II.
Relevant evidence: No