Catherine Jagiellon [SEP] father
as the youngest daughter of King Sigismund I the Old of the Polish-Lithuanian Commonwealth and his wife Bona Sforza of Milan. Catherine became the spouse of King John III of Sweden and mother of the future Sigismund III Vasa, King of Poland. After the death of her father in 1548, she and her sisters Anna and Sophia moved to Masovia with their mother. After their mother's departure to Italy in 1558, they lived there alone. The sisters were not close to their brother Sigismund II Augustus of Poland. Catherine
spring of 1556, Queen mother Bona Sforza returned to her native Italy and her two yet-unmarried daughters, Anna Jagiellon and Catherine Jagiellon, moved to Vilnius. It seems that the three women became close. In summer 1558, the royal family returned to Poland. In October, Catherine became severely ill, but the cause of the illness is unknown as she would not allow Polish doctors near her. When her father sent a couple of Austrian doctors, they reported only high fever and chills. She recovered somewhat only in