The Duchy of Zator was one of many Duchies of Silesia.
It was split off the Duchy of Oświęcim, when after eleven years of joint rule the sons of Duke Casimir I in 1445 finally divided the lands among themselves, whereby his eldest son Wenceslaus received the territory around the town of Zator. The fragmentation of the duchy continued after Wenceslaus' death in 1468, when in 1474 his sons Casimir II and Wenceslaus II as well as Jan V and Władysław again divided the Zator territory in two along the Skawa river.
After the death of Casimir II in 1490 however both parts of the duchy were reunited, and in 1494 Jan V as the last surviving brother became its sole ruler. As Jan himself had no heirs, he decided in the same year to sell the duchy to King John I Albert of Poland, under a guarantee that he would remain duke until his death. Jan was killed in 1513 and Zator was united with Poland. At the General sejm of 1564, King Sigismund II Augustus issued privileges of incorporation recognizing both Duchies of Oświęcim and Zator as part of the Polish Crown into the Silesian County of the Kraków Voivodeship, although the Polish kings retained both ducal titles and the name of the Duchy survived in the legal acts (it had however no special privileges).
Zator [ˈzatɔr] (German: Neuenstadt an der Schaue, Wymysorys: Naojśtaod) is an old town on the Skawa river within Oświęcim County, Lesser Poland Voivodeship (since 1999) in southern Poland. From 1975 to 1998 it belonged to the Bielsko-Biała Voivodeship. It is the administrative seat of the Gmina Zator. According to data from December 31, 2008, Zator was inhabited by 4779 people.
The city, located on the Skawa river, is well known for pisciculture, especially carp, and periodic event called Zatorskie Dni Karpia. Zator is the main city of the Carp Valley.
Originally a part of Lesser Poland, the area was acquired by the Silesian Piast Duke Władysław of Opole by an 1274 agreement with the Polish Princeps Bolesław V the Chaste. Zator then belonged to the Upper Silesian Duchy of Opole and after Władysław's death in 1281 fell to the Duchy of Cieszyn. It received town privileges in 1292.
From 1315 on Zator belonged to the Duchy of Oświęcim split off Cieszyn and in 1445 even became the capital of a Piast duchy in its own right, the Duchy of Zator under Duke Wenceslaus I, a Bohemian vassal. It finally fell back to the Kingdom of Poland, when in 1494 Wenceslaus' son Jan V sold his lands to King John I Albert.