 Complete the following phrase:  Henry II in 1239 had to resign the regency of Upper Silesia in favour of his cousin Mieszko II the Fat. He anew defended Lubusz, this time against the forces of the Ascanian margraves of Brandenburg, and in 1241 granted it to his second son Mieszko. The hopes for a re-unification of the Polish lands under the Silesian Piasts ended with the Mongol invasion of Poland and Henrys death at the 1241 