Question: In what year did Sigismund Casimir's mother die?
Sentence (from "Sigismund Casimir"): Sigismund Casimir, Crown Prince of Poland (Polish: "Zygmunt Kazimierz Waza" ), (1 April 1640 – 9 August 1647) - was the only legitimate son of King Władysław IV and his first wife Queen Cecilia Renata.
Relevant evidence: Yes