Mieszko I Tanglefoot in 1163, and thanks to the intervention of the Emperor Frederick Barbarossa, Mieszko and his older brother Bolesław I the Tall returned to Silesia. Mieszko and Bolesław I the Tall co-ruled the Duchy of Wrocław during the period 1163–1173. At first, their rule did not extend over the major Silesian cities, which remained under the control of Bolesław IV the Curly, the current High Duke of Poland. The brothers retook them in the year 1165, taking advantage of Bolesław IV's involvement in a crusade against the Prussians. However, soon Mieszko began his efforts to obtain his own Duchy, maybe in
Mieszko I of Poland Mieszko allied his country with Sweden against Denmark. The alliance was sealed with the marriage of Mieszko's daughter Świętosława with the Swedish king Erik. The content of the treaty is known from the not entirely reliable, but originating directly from the Danish court tradition account given by Adam of Bremen. In this text, probably as a result of confusion, he gives instead of Mieszko's name the name of his son Bolesław: Mieszko decided on the alliance with Sweden probably in order to help protect his possessions in Pomerania from the Danish King Harald Bluetooth and his son Sweyn. They may