In the Battle Hostile_encounter of Cedynia or Zehden , an army of Mieszko I of Poland defeated Conquering forces of Hodo or Odo I of Lusatia on 24 June 972 , near the Oder river .

Whether or not the battle Hostile_encounter actually took place Process_start near the modern-day town of Cedynia is disputed Quarreling in modern scholarship .

Mieszko I , Poland 's first documented Recording ruler based in Greater Poland , had successfully campaigned Military_operation in the Cedynia area , then a West Slavic tribal territory also coveted by Holy Roman Emperor Otto I and German nobles .