It was established about 1315 on the Lesser Polish lands east of the Biała river held by the Silesian branch of the Polish royal Piast dynasty. Briefly semi-autonomous, with its capital in Oświęcim, it was finally sold to the Kingdom of Poland in 1457. Annexed by the Habsburg Empire in 1772, the remaining ducal title ceased to exist in 1918 with the lands being reincorporated into the Second Polish Republic.
History
The duchy was created in 1315 in the aftermath of the 12th century fragmentation of Poland on these southeastern estates of the original Duchy of Silesia, which the Polish High Duke Casimir II the Just had split off the Seniorate Province and granted to the Silesian duke Mieszko IV Tanglefoot in 1177. From 1281 onwards, the area had been part of the Silesian Duchy of Cieszyn until after the death of Duke Mieszko I in 1315, the lands of Oświęcim east of the Biała were split off from it as a separate duchy for Mieszko's son Władysław. In 1327 his heir Duke Jan I the Scholastic paid homage to King John of Bohemia and likewise many other Silesian duchies, Oświęcim became a vassal of the Bohemian Crown.
In 1445 the duchies of Zator and Toszek were created from some the lands of the duchy.[1] Though the Duchy of Oświęcim had fallen under the Bohemian vassalage, it was re-united with Poland in 1454, when the last duke, Jan IV, declared himself a vassal of the Polish king Casimir IV Jagiellon. Jan had no male heirs and sold his duchy to King Casimir for the price of 3,000,000 Prague groschen three years later.
Casimir I (son of Przemysł Młodszy, due to division in 1414 of Oświęcim, Toszek and Strzelin (in Strzelin until 1427))
1433/4-1484
Przemysław of Toszek (son of Casimir I, also prince of Toszek due to its division in 1445)
1433/4-1456
Jan IV (Janusz) (brother of Przemysław Toszecki and son of Kazimierz I, also prince of Toszek, from 1445 due to a division of Oświęcim, 1465-1482 Gliwice, abdicated (Oświęcim transferred to Crown of Poland), d. 1496)
Rulers claiming the ducal title after partition of Poland
^Prokop, Krzysztof Rafał (2002). Księstwa oświęcimskie i zatorskie wobec Korony Polskiej w latach 1438-1513. Dzieje polityczne (in Polish). Kraków: PAU. p. 151. ISBN83-88857-31-2.
^Zoepfl, Heinrich (1859). Corpus Juris Confoederationis Germanicae (in German). Frankfurt am Main: H.L. Brönner. p. 63.