The Battle of Mątwy (Polish: Bitwa pod Mątwami) was the biggest and bloodiest battle of the so-called Lubomirski Rokosz, a rebellion against Polish King John II Casimir, initiated by a magnate and hetman, Jerzy Sebastian Lubomirski. It took place on 13 July 1666 in the village of Mątwy (now a district of Inowrocław), and ended in rebel victory. Royal army of the Polish–Lithuanian Commonwealth lost almost 4000 of its best and most experiences soldiers, who were murdered by Lubomirski's men. Rebel losses are estimated at approximately 200.