In what year did Sigismund Casimir's mother die?
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. He was named after his grandfather Sigismund III, and uncle John Casimir.
Casimir I of Warsaw Casimir I of Warsaw (pl: "Kazimierz I warszawski"; 1329/31 – 26 November/5 December 1355), was a Polish prince member of the House of Piast, Duke of Czersk during 1341-1349 jointly with his brother, since 1345 ruler over Rawa Mazowiecka jointly with his brother, since 1349 sole ruler over Warsaw, since 1351 sole ruler over Sochaczew, Polish vassal since 1351.