Henry I of Germany conquered Brandenburg in 928–929 and imposed tribute upon the tribes up to the Oder. By 948 his son Otto I had established German control over the many remaining pagans, who were collectively referred to as Slavs or Wends by contemporaries. Slavic settlements such as Brenna, Budišin (Bautzen), and Chotebuž (Cottbus) came under German control through the installation of margraves. The main function of the margravial office was to defend and protect the marches (frontier districts) of the Kingdom of Germany. After the death of the margrave Gero the Great in 965, the vast collection of marches (a "super-march") was divided by Otto into five smaller commands. The Northern March was one of these. The others were the Eastern March, the March of Merseburg, the March of Meissen, and the March of Zeitz.