Nicholas I, Duke of Troppau in the context of "Wenceslaus II of Bohemia"

The Principality of Opava (Czech: Opavské knížectví; Polish: Księstwo Opawskie) or Duchy of Troppau (German: Herzogtum Troppau) was a historic territory split off from the Margraviate of Moravia before 1269 by King Ottokar II of Bohemia to provide for his natural son, Nicholas I. The Opava territory thus had not been part of the original Polish Duchy of Silesia in 1138, and was first ruled by an illegitimate offshoot of the Bohemian Přemyslid dynasty, not by the Silesian Piasts like many of the neighbouring Silesian duchies. Its capital was Opava (Troppau) in the modern-day Czech Republic.

From 1337 onwards, the Přemyslid dukes also ruled the adjacent former Piast Duchy of Racibórz, whereupon Opava became united with the Upper Silesian lands. When the Opava branch became extinct in 1464, it fell back to the Bohemian Crown, from 1526 part of the Habsburg monarchy. In the final three centuries of its existence, the duchy was ruled by the House of Liechtenstein. It was dissolved with the Austro-Hungarian Empire in 1918, but the title of Duke of Troppau and Jägerndorf still exists, belonging to a present-day monarch, Prince Hans-Adam II of Liechtenstein. The Duchy of Jägerndorf (Krnov) was another of the Silesian duchies.