Henryk IV Probus
When Władysław's second son Casimir became Duke of Bytom, he at first ruled jointly with his brother Duke Bolko I of Opole and from 1284 on alone. The conflict with his Piast cousin Duke Henryk IV Probus of Silesia-Wrocław led Casimir to seek shelter from King Wenceslaus II of Bohemia and in 1289 he became the first Silesian Piast duke to submit himself under Bohemian overlordship.