| 10 June 1294|
| Casimir I of Kuyavia, Euphrosyne of Opole|
Władysław I the Elbow-high
Konrad I of Masovia, Agafia of Rus, Casimir I of Opole, Viola, Duchess of Opole
Casimir II the Just, Helen of Znojmo
Casimir II of Łęczyca (pl: Kazimierz II łęczycki; ca. 1261/62 - 10 June 1294), was a Polish prince member of the House of Piast, Duke of Brześć Kujawski during 1267–1288, Duke of Dobrzyń during 1275–1288 and Duke of Łęczyca since 1288 until his death.
He was the fourth son of Casimir I of Kuyavia, but the second born from his third marriage with Euphrosyne, daughter of Casimir I of Opole. He was probably named after both his father and maternal grandfather.
Casimir II of Łęczyca Wikipedia
After the death of his father in 1267, Casimir II, together with his full-brothers, inherited their share of his lands under the regency of their mother until 1275, when they jointly ruled. Casimir II inherited his own domain in 1288, when after the death of his childless half-brother Leszek II the Black he received the Duchy of Łęczyca, situated in the centre of Poland.
In 1289 Caismir II, together with his brother Władysław I the Elbow-high, supported the campaign of Bolesław II of Płock for the throne of Kraków. The joint Płock-Brześć-Łęczyca forces defeated on 26 February the Silesian troops commanded by Henry III of Głogów, Bolko I of Opole and Przemko of Ścinawa at the Battle of Siewierz. For unknown reasons, shortly after Bolesław II renounced to his claims over the Seniorate, an event who was used by Władysław I to conquer Lesser Poland for himself. With the close cooperation of Casimir II, Władysław I began a war against King Wenceslaus II of Bohemia. This policy suffered a defeat in the fall of 1292, when as a result of a Bohemian expedition Casimir II and his brother were captured by Wenceslaus II. In the subsequent peace treaty signed on 9 October of that year, both brothers were forced to pay homage to the Bohemian King.
Casimir II and Władysław I didn't give up, however, to their ambitious plans to conquer Lesser Poland and on 6 January 1293 they met at Kalisz with Przemysł II of Greater Poland and Jakub Świnka, Archbishop of Gniezno and began conversations for a joint action for the recovery of Kraków. They concluded a secret agreement whose exact details are only known for the copy gave to the Archbishop; under this treaty, Casimir II, Władysław I and Przemysł II are obliged to pay annually the amount of 300 pieces of fine silver from salt mines after the recovery of the capital of Lesser Poland.
Casimir II was killed in the Battle of Trojanów on 10 June 1294 on the bank of the Bzura river, while chasing a Lithuanian troops under the command of Vytenis, who escaped after an attack to Łęczyca on 4 June. Jan Długosz described the event as follows:
Because Casimir II died unmarried and childless, his principality was inherited by Władysław I the Elbow-high. It's unknown where he was buried, probably in the The Collegiate church of St. Mary and St. Alexius in Tum near Łęczyca.