His work on Albrecht the Bear, the first Margrave of Brandenburg, contains the first known mention of the story of how Albrecht converted the Slavic Prince Jaxa to Christianity.
Hence, Mieszko the Old, Duke of Greater Poland (later High Duke of Poland) actively supported Jaxa and the Slavic rebellion, fully aware that as long as German nobles were busy fighting Slavs to the west, they could not intervene into Polish affairs.
Treptow-Köpenick | A male ''Labidura riparia'' specimen in Köpenick | JAXA | Der Hauptmann von Köpenick (1956 film) | Jaxa of Köpenick | Jaxa |