Question: When did Bolesław Iii Of Płock's father die?
Sentence (from "Bolesław III of Płock"): Bolesław III of Płock (pl: "Bolesław III płocki"; 1322/30 – 20 August 1351), was a Polish prince member of the House of Piast, Duke of Płock since 1336 (under regency until 1340), ruler over Wizna and Sochaczew since 1345, formally a vassal of the Kingdom of Bohemia during all his reign.
Relevant evidence: No