Question: Wilhelm von Lenz, was a Baltic German Russian official and writer, and was a friend of many mid-century Romantic composers, including Hector Berlioz, that died on which date, was a French Romantic composer, best known for his compositions "Symphonie fantastique" and "Grande messe des morts" (Requiem)?
{'answer': '8 March 1869', 'supporting_facts': [['Wilhelm von Lenz', 0], ['Hector Berlioz', 0]]}