https://en.wikipedia.org/wiki/Casimir_III_the_Great
Casimir III the Great (Polish: Kazimierz III Wielki; 30 April 1310 – 5 November 1370) reigned as the King of Poland from 1333 to 1370. He also later became King of Ruthenia in 1340, and fought to retain the title in the Galicia-Volhynia Wars.He was the third son of Ladislaus the Short and Jadwiga of Kalisz, and the last Polish king from the Piast dynasty.