Question: When did Bolesław Iii Of Płock's father die?
Sentence (from "Wenceslaus of Płock"): Wenceslaus (Wańko) of Płock (Masovian dialect: "Wańko Puocky"; 1293/97 – 23 May 1336), was a Polish prince member of the House of Piast, Duke of Płock since 1313 and vassal of Bohemia from 1329.
Relevant evidence: Yes