Along with most of Silesia, in 1327 the Duchy of Opole came under the sovereignty of the Kingdom of Bohemia, itself part of the Holy Roman Empire. In 1521 the Duchy of Racibórz ("Ratibor") was inherited by the Duchy of Opole, by then also known by its German equivalent – Oppeln. The second castle of Opole was probably founded in the 14th century by duke Vladislaus II, though some sources claim that it was originally a wooden stronghold of Opole's castellan dating into 12th century.