At Christmas 1009, after his father was killed in a fierce struggle with Margrave Werner of the Northern March,[2] Dietrich was vested with the County of Wettin in the Saxon Hassegau by King Henry II of Germany at Pöhlde.
Upon the death of his uncle Frederick I, who had died without male issue in 1017, Dietrich inherited Eilenburg and Brehna.
In 1018, Dietrich II and his brother-in-law, Margrave Herman I of Meissen acted as witnesses when the Peace of Bautzen was concluded between Emperor Henry II and the Polish ruler Bolesław I the Brave, ending a lengthy German–Polish War.
Bolesław's son and successor Mieszko II lost Lusatia and finally had to renounce his claims in the 1033 Treaty of Merseburg.
According to the Annalista Saxo chronicles, Dietrich played a key role in the emperor's campaign and in turn could succeed the Lusatian margrave Odo II in 1032.