 Charles the Younger launched a campaign against the Slavs in Bohemia in 805, and after killing Duke Lecho of the Bohemians, Charles himself crossed the Saale with his army and killed Sorbian princes Miliduch and Nussito, near modern-day Weißenfels, in 806.The region was laid to waste, upon which the other Slavic chieftains submitted and gave hostages.In 808, Danish king Gudfred, after building the Danevirke (for the defence of a possible Frankish attack), crossed into Obotrite area at Reric (modern Wismar) and forced them to acknowledge him as their suzerain.