 Dedo married, before 985, Thietburga, the daughter of Dietrich of Haldensleben, Margrave of the Nordmark.In the years 974 to 985 Dedo I was involved in the rebellion of Duke Henry II of Bavaria against the Holy Roman Emperor Otto II and later against his son Otto III, until June 985, when the Bavarian Duke was finally subjugated in Frankfurt.In 976 Dedo commanded a Bohemian army, conquered the March of Zeitz and robbed the Bishop's Church.