Italian by birth, Polish by destiny – Bona Sforza, the ambitious princess from Milan, brought Renaissance flair to the Jagiellonian court and left a lasting mark on Poland’s politics, economy, and even its cuisine. Her life was a tale of power, ambition, and influence – stretching from Milan to Kraków, and ending in a mysterious death in Bari.

Bona Sforza| Бона Сфорца | 博娜·斯福尔扎 | ボナ・スフォルツァ | 보나 스포르차 | بونا سفورزا

Bari is a city that is heard of in Poland from early childhood history lessons. In this city, one of the most influential queens in Polish history, Bona Sforza, was living before and after her stay in Poland. She became the Queen of Poland and Grand Duchess of Lithuania through her marriage to Sigismund I of Poland. It was only while staying with an Italian family near Bari that I learned that Bona Sforza was a significant figure in Bari, as well. Furthermore, that her modest sarcophagus is placed on the altar in the Basilica of Saint Nicholas in Bari.

Isabella sought to arrange a favorable marriage for Bona to regain political influence and her former possessions. Despite initial unsuccessful attempts due to Isabella’s unfavorable political position, with the support of the Habsburgs, she eventually succeeded in arranging Bona’s marriage to the widowed Polish King Sigismund I.

In 1518, Bona Sforza married King Sigismund I of Poland, becoming Queen of Poland and Grand Duchess of Lithuania.

A Queen and Reformer

Her role as the Queen of Poland was marked by significant administrative reforms, among which the establishment of a permanent tax system was a major achievement. Although it must be said that she imposed and enforced these taxes with a firm hand. Prior to her influence, the Polish-Lithuanian Commonwealth relied on irregular and often arbitrary taxation methods that were not only inefficient but also prone to exacerbating tensions between the monarchy and the nobility. By introducing a more systematic and regularized tax system, she brought about greater fiscal stability and predictability, which was essential for the effective governance and financial planning of the state. In addition to these fiscal reforms, Bona Sforza made concerted efforts to reduce the influence of the nobility by curbing their traditional privileges and powers, thereby centralizing authority under the monarchy.

Beyond her domestic reforms, Bona Sforza was deeply engaged in the foreign affairs of the Polish-Lithuanian realm. She openly opposed the growing influence of the Habsburgs in Central Europe and sought to counterbalance it through alliances with France and the Ottoman Empire. Her foreign policy was closely tied to her dynastic interests, as she worked to secure titles, lands and advantageous marriages for her children. Although some of her efforts were ultimately frustrated, she remained a shrewd political operator, whose ambitions extended well beyond the borders of her adopted country.

Bona Sforza played a notable role in the development of Renaissance culture in Poland. Hailing from Italy, she brought with her the refined tastes of the Italian courts and introduced them to the Polish royal household. She actively patronised artists, architects and craftsmen, many of whom she brought from her native land, leaving a lasting mark on the visual and architectural landscape of the kingdom. Under her influence, Wawel Castle was transformed with elegant arcaded courtyards in the Italian style. Beyond architecture, she encouraged literary and educational pursuits, helping to shape a more sophisticated and cosmopolitan court culture.

She also had a considerable impact on Polish agriculture and cuisine. She introduced important agricultural reforms, including new crops and farming techniques. While the idea that she single-handedly brought vegetables to Poland is somewhat exaggerated, she did play a significant role in promoting their wider use at the royal court and among the nobility. As a noblewoman from Italy – where Renaissance culinary culture was particularly rich and diverse – she brought with her knowledge of produce that was not commonly used in Poland at the time. Her influence contributed to a gradual shift in dietary habits, particularly among the upper classes.

Power Struggles and Exile

Bona Sforza, towards the end of King Sigismund I’s reign and after his death in 1548, faced increasing animosity from the Polish nobility due to her strong political influence and centralizing reforms. Her relationship with her son, Sigismund II Augustus, became fraught with tension, as well. After he ascended to the throne, their differing views on state affairs exacerbated the strain in their relationship. A major source of conflict was also her son’s marriage to Barbara Radziwiłł from one of the most influential Polish-Lithuanian noble families. Bona viewed it as politically damaging and personally threatening, as it would strengthen his wife’s family influence at court while diminishing her own.

Consequently, for long eight years she moved with her daughters to Brodnica in Mazovia Poland. Finally she made the decision to leave Poland and return to Italy to Bari, marking the end of her direct involvement in Polish politics. Bona’s life came to an abrupt and mysterious end in 1557.

The Duchess of Bari

And here yet another fact from her life comes to light. Following her marriage to Sigismund I the Old in 1518, Bona was formally granted hereditary fiefs in southern Italy by Emperor Charles V of the Habsburg dynasty. These included the Duchy of Bari, the Principality of Rossano, as well as Modugno and Bitonto. These were highly lucrative estates situated in the Kingdom of Naples. Bona derived substantial income from them. She maintained financial independence and even loaned money to the Polish royal treasury. She was one of the wealthiest individuals in the Polish-Lithuanian Commonwealth, and she handled her finances with remarkable diligence and care. For decades, even while residing in Poland, she administered her southern Italian fiefs through a network of trusted agents and correspondence. From the royal court in Kraków, she managed financial affairs, collected revenues, and oversaw local governance in the Duchy of Bari. This transregional management made her one of the most financially independent monarchs in Europe at the time.

When she eventually returned to Bari in 1556, she resumed direct rule and implemented a series of administrative and economic reforms. She strengthened tax collection, invested in urban infrastructure, and reasserted political control over her domains. Her presence in Bari reestablished the court as a center of local authority and Renaissance patronage — yet also drew the attention and hostility of the Spanish crown, particularly Philip II (son of Charles V), under whose rule the Kingdom of Naples now fell.

Bona died under suspicious circumstances. One of the historical hypotheses that has not been conclusively confirmed is the theory that she was poisoned by her secretary, Gian Lorenzo Pappacoda, who allegedly acted under orders from the Spanish crown. A forged will emerged, one that transferred her Italian holdings not to her son, as she had intended, but instead to Philip II. Poland’s diplomatic protests and claims were entirely ignored by the Spanish authorities.

She was buried in the Basilica of Saint Nicholas in Bari.

When you enter the Basilica of St. Nicholas, at first you do not see the sarcophagus of Bona, then you only see it from behind the baldachin, which is located in front of the altar. To see the sarcophagus and the sculpture depicting Bona immersed in prayer, you have to approach the altar closer.