Question: What is the date of death of Johann Christian Friedrich Hæffner's wife?
Sentence (from "Johann Christian Friedrich Hæffner"): The starting point of this tradition is usually set to a performance of "Under Svea banér" (words by P.D.A. Atterbom, music by Hæffner) by a student choir celebrating the war hero "Klingspor" on 24 October 1808.
Relevant evidence: No