 In 1018, Theodoric 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.From 1029, Emperor Conrad II again waged war against Poland.Bolesław's son and successor Mieszko II lost Lusatia and finally had to renounce his claims in the 1033 Treaty of Merseburg.