On 20 March 1241, units of the Mongol Army reached the Oder near Raciborz, and began to cross the river. Duke Mieszko II the Fat, aware of this, decided to attack the invaders while they were busy trying to get across the Oder. After the battle, Mieszko's army headed towards Legnica, where Christian forces under Duke Henry II the Pious concentrated to engage the Mongols in the Battle of Legnica.
Sources
Piastowie. Leksykon biograficzny, wyd. 1999, str. 397
Wielka Historia Polski cz. do 1320, wyd. Pinexx 1999, s. 187-188
Stanislaw Krakowski, Polska w walce z najazdami tatarskimi w XIII wieku, wyd. MON 1956, str.136-137