The Battle of Trojanów was a battle on 10 June 1294, on the banks of the Bzura River, a battle took place between the Lithuanians returning from a looting raid on Łęczyca and the pursuing army of the Duke of Łęczyca Casimir II. The Lithuanians, under the command of Duke Vytenis, on Pentecost, June 4, invaded the city of Łęczyca and captured the fortified collegiate church at Tuma. They plundered everything of any value, the priests and people were taken captive and the collegiate church itself was set on fire. During their retreat, they were caught up by the troops of Duke Casimir II at Trojanów. Then Duke Bolesław II of Masovia (married to the daughter of the Lithuanian Duke Traidenis) led to a truce between Casimir II and the Lithuanians, but at the least expected moment the Vytenis broke it and attacked Casimir II, as a result of which the Duke of Łęczyca was killed, and Bolesław II's life was saved by Lawrence, Castellan of Biała. This was the greatest victory of the Lithuanians in their battles against the Poles (in fact against the Łęczyca knights).