Sophia Jagiellon, Margravine of Brandenburg-Ansbach

In 1468, Sophia was first betrothed to Archduke Maximilian of Austria, son and heir of Emperor Frederick III. Then, on 8 April of the same year, Protas Černohorský z Boskovic, Bishop of Olomouc, appeared as a representative of King Matthias Corvinus of Hungary, asking the hand of Sophia, although soon Matthias preferred the hand of Sophia's elder sister, Hedwig. A marriage to Maximilian seemed more likely for Sophia, mostly because she and her sisters were all attractive brides for European nobility, since they all had claims to the thrones of Austria and Luxembourg through their mother Elisabeth. There could have been a chance that one could become Duchess of Austria or Luxembourg and transfer their patrimony to a husband and his family.

Hedwig's marriage plans with Matthias fell through when her father made an alliance with Matthias' main enemy, George of Poděbrady. Shortly after, the wedding plans between Maximilian and Sophia similarly fell through.

It's unknown when exactly started the negotiations for a marriage between Sophia and Prince Frederick of Brandeburg, son of Elector Albrecht III Achilles. There is a presumption that the idea could emerged in the summer of 1470, when Polish deputies Dziersław z Rytwian and Stanisław Ostroróg visited Brandenburg.[3] In 1473 the Polish royal representatives Paweł Jasieński (starost of Chełm and Belz) and Stanisław Kurozwęcki led the negotiations for the marriage between Sophia and Frederick, which ended with the signing of the formal betrothal on 7 December of that year in the city of Cadolzburg.

As for the political motives of this marriage, Sophia's father Casimir IV sought allies among the Germans, since he was concerned with the influence of the Holy Roman Emperor Frederick III, who supported the rule of the Polish prince Vladislaus in Bohemia. By the other hand, Elector Albrecht III Achilles, concerned about the growing power of Matthias Corvinus (who was threatening to take some of Albrecht's lands), decided to sought an alliance with his opponents, the Jagiellonian dynasty.[4]

Terms concerning the marriage had been negotiated for almost two years. Originally the marriage contract was planned to be signed on 20 March 1474 and on 23 June 1474, during a meeting between representatives of both Brandenburg and Poland in Pniewy. Finally, the marriage contract was signed in October 1475 at Poznań; in representation of the Electorate of Brandenburg signed Friedrich II Sesselmann, Bishop of Lubusz, while Stanisław Kurozwęcki signed as a representative of the Kingdom of Poland. Sophia's dowry was established in 32,000 florins.

On 11 November 1475 Elector Albrecht III Achilles gave as a Bride price for his future daughter-in-law the amount of 64,000 florins. Originally, the wedding of Sophia and Frederick was to take place in Poznań, but the Elector opted for Frankfurt instead.

On 13 January 1479 Sophia, accompanied by family, left Piotrków Trybunalski for Frankfurt. She was accompanied, among others, by Andrzej Oporowski, Bishop of Przemyśl, voivodes Maciej z Bnina Moszyński and Mikołaj z Kutna, and by Piotr Kurozwęcki, Marshal of the Court.

On 14 February 1479 Sophia and Frederick were married at Frankfurt. According to the Polish chronicler Jan Długosz, the wedding was not extravagant and even the royal courtiers were not banqueted. In addition, the king's senators, knights and other clerics, who had traveled with his daughter to Frankfurt, hardly received any gifts.[5]

Difficulties arose with the payment of Sophia's dowry. According to the marriage contract, Casimir IV was supposed to pay the first installment of 6,000 guilders by 25 December. Unable to do so, the Polish king asked for a deferment, to which Albrecht III agreed. In view of the non-payment of her dowry, Sophia was unable to take possession of her dower lands.

On 11 March 1486, Sophia's father-in-law Albrecht III Achilles died. Her husband Frederick and brother-in-law Siegmund inherited the Franconian domains of the Hohenzollern dynasty. Siegmund took Kulmbach,[6] while Frederick received Ansbach. Sophia thus became in the Margravine consort of Ansbach. Shortly after, they received in their domains the visit of Holy Roman Emperor Frederick III.

During all this time, a continuing problem was the payment of Sophia's dowry. In 1489, Sophia's brother Vladislaus II promised Frederick he would pay the rest of the money his father owed. In 1493, Frederick sent envoys to Poland on payment of dowry. On 30 September 1495, Sophia personally wrote a letter to her brother asking for the promised money. The dowry was never completely paid off until after Sophia and Frederick's deaths. The last of the money was paid to their children in several installments - respectively in 1533, 1535 and 1537.

Sophia's husband kept in touch with her brothers: in the spring of 1494, he took part in the convention in Levoča, which was attended by Vladislaus II, John I Albert, Sigismund (the future King Sigismund I the Old) and Cardinal Frederick. Frederick also planned to strengthen family ties between the Hohenzollerns and Jagiellons: Barbara, Sophia's younger sister, was suggested to marry Joachim, Hereditary Elector of Brandenburg, Frederick's nephew, and Vladislaus II could married with Anna, Joachim's sister. Finally, these marriage plans never taken place.[7]

After the death of his brother Siegmund unmarried and childless in 1495, Frederick also inherited Bayreuth, thus Sophia also became in Margravine consort of Brandenburg-Kulmbach.

By a letter wrote by her mother-in-law Anna of Saxony dated 13 April 1505 was known that Sophia was seriously ill. Four months later, on 30 August, her mother died.

In March 1509, Sophia and her husband were present in Prague for the coronation of her nephew Louis II Jagiellon.

Exhausted by over three decades of constant pregnancies and miscarriages,[lower-alpha 1] Sophia died on 5 October 1512 in Ansbach. She was buried in the monastery of Heilsbronn. After the death of Sophia, her husband arranged an extremely boisterous wake: 1,500 cups of wine were drunk and 2 oxen and 600 fish were eaten over the course of the night.[8]