Žyhimont II Aŭhust (1520-1572), Grand Duke of the Grand Duchy of Lithuania (GDL) and king of Poland (1548-1572). Son of Žyhimont I and the last monarch of the Jahajła dynasty. Elected Grand Duke of the GDL and king of Poland (1529) at the age of ten, Žyhimont Aŭhust (Sigismund Augustus) began fulfilling the duties of Grand Duke of the GDL in 1544. In 1547, he married Barbara Radzivił, who came from the most powerful magnate family of the Grand Duchy. Two of her brothers had considerable influence on the young Grand Duke, to the chagrin of his parents. According to legend, Barbara was poisoned (she died in 1551) as a result of that conflict.
In his domestic policy, Žyhimont II sought to increase the rights of the middle gentry, supported reforms of the treasury, courts, and army, and made steps toward the return to the state of lands that had been distributed to magnates since 1504. A part of the finances raised through this measure was spent on building the Polish navy. Žyhimont Aŭhust was tolerant of the Reformation and non-Catholic confessions. By his Charter of 1563, he fully equalized the rights of the Orthodox and Catholic gentry and confirmed the updated Code of the GDL in 1566. As a man of the Renaissance, the monarch was generous in support of artists, architects, musicians, and actors. Cultural activities in his realm, marked by the vigorous spread of humanist ideas and the Reformation, flourished throughout his reign. Toward the end of his years, he had to concede to the demands of the Catholic hierarchy to invite Jesuits to Poland (1564) and the GDL (1569) in order to counteract the Reformation (see Counter-Reformation). He strongly favored the fusion of the kingdom and the Grand Duchy, which was achieved through the Union of Lublin (1569). The primary reason for this move was military pressure from Russia, with which the GDL fought in the Livonian War. During Žyhimont's reign Poland was successful in retaining her homage of the duke of Prussia and improved relations with Sweden.
