Question: What is the date of death of Prince Friedrich Karl Of Prussia (1828–1885)'s mother?
Sentence (from "Prince Friedrich Karl of Prussia (1828–1885)"): He defeated the Austrian army at the Battle of Königgrätz in 1866 and the French Army of the Rhine at the Battle of Mars-la-Tour, overseeing the extinction of the Army of the Rhine at the Siege of Metz in 1870.
Relevant evidence: No