Duchy of Racibórz (Polish: Księstwo raciborskie, Czech: Ratibořské knížectví, German: Herzogtum Ratibor) was one of the duchies of Silesia, formed during the medieval fragmentation of Poland into provincial duchies. Its capital was Racibórz in Upper Silesia.
After the death of Mieszko's grandson Duke Władysław Opolski in 1281, his sons again divided the Duchy of Opole and Racibórz and in 1290 the Duchy of Racibórz was recreated again, assigned to Władysław's youngest son Przemysław. Racibórz at that time comprised the lands of Wodzisław, Żory, Rybnik, Mikołów and Pszczyna, while some of the territory of was used for the creation of the duchies of Cieszyn and Bytom under Przemysław's brothers.
A large number of place names of German origin in the southern part of the Duchy are the effect of medieval Ostsiedlung. [1]
In 1327 Przemysław's son Duke Leszek paid homage to King John of Bohemia, whereafter his duchy became a Bohemian fief. After Leszek died without issue in 1336, King John seized the duchy and granted it to the Přemyslid Duke Nicolas II of Opava (Troppau), forming the united Duchy of Opava and Racibórz. The Duchy would suffer several territorial changes until in 1521 it was again merged with Opole under Duke Jan II the Good. As a Duchy of Opole and Racibórz, after Jan's death in 1532 it fell back to the House of Habsburg, Bohemian kings since 1526. The fief was given in pawn to Margrave George of Brandenburg-Ansbach from the House of Hohenzollern. From 1645 to 1666 as part of the Duchy of Opole and Racibórz it was held by the Polish House of Vasa. It was annexed and incorporated into the Kingdom of Prussia by the 1742 Treaty of Breslau.