Dedi inherited the Ostmark from its last dynast, the childless Odo II, because he had married his sister, Oda (died before 1068).
When Otto his stepson died, Dedi married his widow, Adela of Louvain, and in her name claimed the Meissen March.
With him in his revolt was Albert II of Ballenstedt, who raided the monastery of Nienburg, a foundation of the family of Dedi's first wife.
Adela of Louvain for her part aggressively supported her husband, so much so that Lambert of Hersfeld was compelled to call her a saevissima uxor (rough meaning "raging wife").
Adalbert of Bremen, one of the regents of the young king Henry IV, frustrated the Thuringian rebels and preserved the peace in Thuringia and Meissen.