Gero participated in general Saxon campaigns against the Slavs in 957, 959, and 960, as well as campaigning against the Wends and forcing Mieszko I of the Polans to pay tribute, grant land lien, and recognise German sovereignty during Otto's absence in Italy (962–963). Lusatia, according to Widukind, was subjected "to the last degree of servitude." Gero was responsible for subjecting the Liutizi and Milzini (or Milciani) and extending German suzerainty over the whole territory between the Elbe and the Bober. In these lands, the native Slavic populace was reduced to serfdom and "tribute-paying peoples" were converted into "census-paying peasants."