At Bishop Gerold's instigation Helmold wrote his Chronica Slavorum, a history of the conquest and conversion of the Polabian Slavs from the time of Charlemagne (about 800) to 1171.
Ved biskop Gerolds tilskyndelse skrev Helmold sin Chronica Slavorum, en historie om erobringen og konverteringen af de polabiske slavere under Karl den Stores tid (ca. 800) til 1171.