Casimir IV (in full Casimir IV Andrew Jagiellon; ; Lithuanian: ; 30 November 1427 – 7 June 1492) was Grand Duke of Lithuania from 1440 and King of Poland from 1447, until his death. He was one of the most active Polish-Lithuanian rulers, under whom Poland, by defeating the Teutonic Knights in the Thirteen Years' War recovered Pomerania, and the Jagiellonian dynasty became one of the leading royal houses in Europe. The great triumph of his reign was bringing Prussia under Polish rule. The rule of Casimir corresponded to the age of "new monarchies" in western Europe. By the 15th century, Poland had narrowed the distance separating it from western Europe and become a significant factor in international relations. The demand for raw materials and semi-finished goods stimulated trade, producing a positive balance, and contributed to the growth of crafts and mining in the entire country. He was a recipient of the English Order of the Garter (KG), the highest order of chivalry and the most prestigious honour in England. Following Casimir's death in 1492, John I Albert succeeded him as King of Poland, and Alexander Jagiellon was proclaimed Grand Duke of Lithuania. Youth Casimir Jagiellon was the third and youngest son of King Władysław II Jagiełło and his fourth wife, Sophia of Halshany. He often relied on his instinct and feelings and had little political knowledge, but shared a great interest in the diplomacy and economic affairs of the country. Throughout Casimir's youth, Bishop Zbigniew Oleśnicki was his mentor and tutor, however, the cleric felt a strong reluctance towards him, believing that he would be an unsuccessful monarch following Władysław's death. Grand Duke of Lithuania The sudden death of Sigismund Kęstutaitis left the office of the Grand Duchy of Lithuania empty. The Voivode of Trakai, Jonas Goštautas, and other magnates of Lithuania, supported Casimir as a candidate to the throne. However many Polish noblemen hoped that the thirteen-year-old boy would become a Vice-regent for the Polish King in Lithuania. Casimir was invited by the Lithuanian magnates to Lithuania, and when he arrived in Vilnius in 1440, he was proclaimed as the Grand Duke of Lithuania on 29 June 1440 by the Council of Lords, contrary to the wishes of the Polish noble lords—an act supported and coordinated by Jonas Goštautas. When the news arrived in the Kingdom of Poland concerning the proclamation of Casimir as the Grand Duke of