Kazimierz the Great, who ruled from 1333 to 1370, was thus able to inherit from his father a re-united kingdom. Kazimierz guided Poland to prosperity, doubled the country’s size, modernized the army, introduced a legal code, and founded the University of Krakow in 1364. He is the only Piast called “The Great.” However, the Piast line ended with his death in 1370. Because he had no male heir, his nephew, King Louis of Hungary, succeeded him as the king of Poland. In 1384, his daughter Jadwiga, a beloved Polish figure of Piast ancestry, followed Louis. Jadwiga, Queen of Poland is one of the most influential women in Polish history. Pope Saint John Paul II canonized her in 1997 and proclaimed the highly devout Jadwiga “the most Christian Queen.”