Article tells about conditions, in which at the beginning of 15th century, two Silesian duchies Legnica Duchy and Brzeg Duchy were divided. These duchies were joined by law of common succession of descendants of dukes Wenceslaus II (died 1364) and Luis II (died 1398). After this stability period Henry IX waged war (1411-1414) with his brother Luis II on division their father Henry VIII's legacy. Duchy Olawa permanently came into existence and titulatur in sigillum of Luis III between 1420 and 1424. Analysis of documents and seals could also state more pricesily that Henry IX died in 1419 between 19th January and 17th July.
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