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 .

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 .

While Mieszko 's differences with Otto I were settled Resolve_problem by an alliance Cause_to_amalgamate and payment Commerce_pay of tribute to the latter , the nobles whom Otto I had invested with the former Saxon Eastern March , most notably Odo I , challenged Mieszko 's gains Earnings_and_losses .

While Mieszko 's differences with Otto I were settled Resolve_problem by an alliance Cause_to_amalgamate and payment Commerce_pay of tribute to the latter , the nobles whom Otto I had invested with the former Saxon Eastern March , most notably Odo I , challenged Mieszko 's gains Earnings_and_losses .

The battle Hostile_encounter was to determine Deciding the possession Control of the area between Mieszko and Odo .

It ended Process_end in the victory of a Polish army from Silesia , commanded Control by Duke of Opole and Raciborz , Mieszko II the Fat .

Duke Mieszko II the Fat , aware of this , decided Deciding to attack Attack the invaders while they were busy trying to get across the Oder .

After the battle Hostile_encounter , Mieszko ’ s army headed Self_motion towards Legnica , where Christian forces under Duke Henry II the Pious concentrated to engage Participation the Mongols in the Battle Hostile_encounter of Legnica .