The Italian Princess Bona, of the Sforza family, became Queen of Poland in 1518 as the second wife of Sigismund I. At that time no one anticipated how significant a role she would play in European history. She was twenty-seven years younger than her husband, and had been raised at her parents' Italian court in Bari, where she learned the diplomatic skills. Towards the end of her husband's life, when the senile king began to lose interest in matters of state, she practically took over the running of the country. For a long time she also exerted an influence on her only son, Sigismundus Augustus.
Bona was not very popular in Poland. Her situation was not helped by the fact that she tried to introduce the Italian style of governing in the Polish royal court. Purchasing estates, granting offices to loyal courtiers and supporters, and having young Sigismundus Augustus 'elected' king and crowned during his father's lifetime - all of these practices turned the Polish nobility and gentry against her. Yet thanks to a huge dowry and great riches accumulated in the course of her multifarious activities in Poland, the ambitious Italian did gain a lobby supporting her in the Senate and exerted a great deal of power until the end of her sojourn in Poland.
The year 1548, however, brought significant changes. Sigismund I died and the throne passed to Sigismundus Augustus, who did not like his mother's greed and ambition. A struggle for influence began, which vastly undermined the young king's authority. He was particularly ill served by the issue of his marriage to the Lithuanian Barbara Radziwiłłowna. It was the king's second marriage; his first wife, Elisabeth Habsburg, died soon after the wedding without producing an heir. Bona tried to use the Polish lords' mistrust of the Radziwiłł family, for fear of the influence they could bear on Sigismundus Augustus and his policy. The Dowager Queen spread rumours of Barbara's moral misconduct, her infertility and a venereal disease which she had allegedly transferred to the King. Therefore, when the young queen died in 1551 again without giving birth to an heir, Sigismundus Augustus suspected that she had been poisoned by his mother.
In 1554 Bona decided to return to Italy. There was tension between mother and son, since the Queen Mother possessed an enormous fortune and numerous estates throughout the country, both in Poland and Lithuania, which Sigismundus Augustus did not want to lose if she died abroad. He agreed for her to leave Poland in 1556 and return to Bari only if she gave up all her property. She died a year later, poisoned at the behest of the Habsburgs by their confidant, her private secretary Gian Lorenzo Pappacoda.
Although Polish historians have treated Bona rather roughly, one must not forget that Poland owes a rich period of cultural developments specifically to her. Thanks to her and Sigismund I, the Polish Renaissance reached its apogee, with a host of Italian influences in all aspects of life not least the cuisine; artists were commissioned for innumerable works of art, and the grand Renaissance conversion project continued in Wawel Castle in Cracow, along with the erection of the Sigismundian Chapel, burial place of both Sigismund I, his son Sigismundus Augustus and his youngest daughter Anna, The Sigismundian Chapel is one of the finest masterpieces of 16th-century architecture, the grandest specimen of the Italian Renaissance style in architecture north of the Alps. Bona also brought 'włoszczyzna' - 'Italian food' - numerous kinds of vegetables hitherto unknown and ungrown by Polish farmers.