[1] His maternal grandfather Casimir III the Great, the last king of Poland from the Piast dynasty, had no sons and brought him up at his court.

After his grandfather's death in 1370, young Casimir initially became his partial successor, as the last will gave him lands of Dobrzyń, Bydgoszcz, Kruszwica, Złotów and Wałcz as fiefs.

Yet, his ambitions were soon thwarted by Louis I of Hungary, who became the next king of Poland on the grounds of earlier pacts, and nullified the Piast's last will.

[5] She was the daughter of Algirdas and Uliana Alexandrovna of Tver,[5] raised in the Eastern Orthodox faith.

After Casimir’s death of wounds (received in fighting Władysław the White on behalf of King Louis), she married Henry VII, Duke of Lubin and Brzeg.