Catherine Jagiellon (; , Lithuanian: Kotryna Jogailaitė; 1 November 1526 – 16 September 1583) was a princess of the Polish–Lithuanian Commonwealth and Queen of Sweden from 1569 as the wife of King John III. Catherine had significant influence over state affairs during the reign of her spouse. She negotiated with the pope to introduce Counter-Reformation in Sweden. She was the mother of Sigismund III Vasa.
Early life
Catherine Jagiellon was born in Kraków as the youngest daughter of King Sigismund I the Old of the Polish–Lithuanian Commonwealth and his wife, Bona Sforza of Milan.
Catherine was given a thorough Renaissance education by Italian tutors: she was taught to read, write and speak Latin, German and Italian, instructed in conversation, riding, dancing, singing, and playing several musical instruments.
After the death of her father in 1548, she and her unmarried sisters Anna and Sophia moved to Masovia with their mother. In 1556, when her sister Sophia married and left for Germany and her mother departed for Italy, Catherine and her sister Anna were moved to the Palace of Vilnius by their brother Sigismund II Augustus of Poland, to ensure a royal presence in Lithuania. Their stay in Vilnius was described as happy, living in a palace and a court strongly influenced by the Italian Renaissance: Catherine and Anna were allowed to compose their own separate households and socialized with the aristocracy. Catherine was at Vadstena during the rebellion.
Another reason which agitated the nobility against Erik XIV and made them encourage the rebellion of Duke John and his brother Duke Charles was the marriage of Erik to the commoner Karin Månsdotter, which the nobility regarded as an insult. Catherine played some part in the rebellion: she was a friend of one of Erik's enemies, Ebba Lilliehöök, who had an influential position within the nobility, and she was also directly approached by Pontus De la Gardie, who appealed to her to persuade the indecisive John to join the rebellion against the King in protest of his scandalous marriage.
Another significant matter of interest were the rights of her son Sigismund to the Polish throne. She brought up both her children in the Catholic faith, which made Sigismund acceptable as a Polish monarch. After the death of her childless brother Sigismund II Augustus in 1572, she considered her son to have rights to the Polish throne through her. However, after 1569, Poland had become an elective monarchy. This matter, however, also made her significant internationally.
In 1582, she received the former queen, Karin Månsdotter, and saw to it that her confiscated jewellery was returned to her.
Sforza inheritance
Catherine and John III were both eager to be given possession of her part of the Sforza inheritance from her mother in Italy. Queen Catherine had her own personal ambassadors in Rome to protect her interests, Petrus Rosinus and Ture Bielke. The papal curia was willing to help them in this issue, but as her inheritance was situated in the Kingdom of Naples, then belonging to Spain, the pope did not succeed.