sentences:  From 1526, Bohemia, including the fiefdom of Silesia, which Rybnik was a part of, came under the authority of the Habsburg crown.At the beginning of the War of the Austrian Succession between Frederick II of Prussia (the Great) and the Habsburg empress Maria Theresa of Austria, the greatest part of then mainly German-speaking Silesia, including Rybnik, was annexed by Prussia in 1740, which Austria eventually recognized in 1763.Coal mining gained importance for Rybnik's economy as early as the 18th century.