sentences:  From 1560 Bielsko was held by Frederick Casimir of Cieszyn, son of Duke Wenceslaus III Adam, who due to the enormous debts his son left upon his death in 1571, had to sell it to the Promnitz noble family at Pless.With the consent of Emperor Maximilian II, the Promnitz dynasty and their Schaffgotsch successors ruled the Duchy of Bielsko as a Bohemian state country; acquired by the Austrian chancellor Count Friedrich Wilhelm von Haugwitz in 1752, the ducal status was finally confirmed by Empress Maria Theresa in 1754.After the Prussian king Frederick the Great had invaded Silesia, Bielsko remained with the Habsburg Monarchy as part of Austrian Silesia according to the 1742 Treaty of Breslau.