Sophia of Halshany (Lithuanian: Sofija Alšėniškė; Belarusian: Софья Гальшанская, romanized: Sofja Halšanskaja; Polish: Zofia Holszańska;[1] c. 1405 – 21 September 1461 in Kraków), known simply as Sonka, was a princess of Lithuanian Alšėniškiai princely family who was Queen of Poland as the fourth and last wife of Jogaila, King of Poland and Supreme Duke of Lithuania.

[4] Her father died when she was young and the family moved to Druck to live with Alexandra's brother Siemion Drucki.

Therefore, Sophia's older sister Vasilisa was married off to Ivan Bielski, son of Jogaila's half-brother Vladimir Olgerdovich, in 1421.

[8] The wedding ceremony, carried out by Matthias of Trakai, Bishop of Samogitia, took place in Navahrudak on 7[9] or 24 February.

There she was met with hostility by supporters of Emperor Sigismund and Princess Hedwig, particularly Zbigniew Oleśnicki, the Tęczyński and Tarnowski families.

[12] For a year, the couple spent time mostly apart: Jogaila travelled to Prussia for the Gollub War, to Lithuania to spend the winter, to Hungary for negotiations with Emperor Sigismund while Sophia stayed in Kraków.

It is likely that the relationship grew closer during that journey as Jogaila took active steps to have Sophia crowned as the queen by Archbishop of Gniezno Wojciech Jastrzębiec.

Sophia received the villages of Stara Zagość and Bogucice Pierwsze as well as 20,000 grzywnas of Prague groschen.

These dates, provided in historical sources, contradict a 1950 study of Casimir's skeleton which found that the bones are of an approximately 18-month-old boy.

[15] In spring 1427, while pregnant with the third child, Sophia was accused of marital infidelity, therefore casting doubt over Władysław's and yet-unborn Casimir's paternity.

That collapsed the strategy to secure hereditary rights in Poland through Lithuania and, in January 1433, Jogaila confirmed resolutions of the congress in Jedlnia.

[18] In December 1431, Princess Hedwig Jagiellon, betrothed to Frederick II, Elector of Brandenburg, died of a year-long illness.

[18] She also supported a project to betroth Władysław and Anne, Duchess of Luxembourg, who was at the time heiress to the Kingdom of Hungary and Bohemia.

[18] After the death of Sigismund, Holy Roman Emperor, Bohemian nobility, mainly Hussites opposing Albert of Austria, elected Casimir IV Jagiellon as their king in March 1438 in Chrudim.

However, the campaign was poorly organized and, after the defeat of Casimir's supporters in Želenice, the army returned to Poland in October 1438.

[20] In December 1438, Polish nobles gathered in Piotrków Trybunalski and proclaimed 14-year-old Władysław to have attained the age of majority.

[21] She actively took part in organizing a confederation "for protection of the king and order in the kingdom," which opposed Oleśnicki and supported Hussites, in Nowy Korczyn.

With Władysław in Hungary, Lithuanian nobles, led by Jonas Goštautas, invited Casimir to Vilnius and elected him as the Grand Duke.

According to Jan Długosz, Sophia's motherly pleas convinced nobles to confirm Casimir as their king in Nowy Korczyn despite Oleśnicki's support to Bolesław.

[24] Her last known political action was sending an envoy to newly elected Pope Pius II to find out his opinions on the Polish–Teutonic War (1454–66).

Even though the translation was not completed, the work, known as Bible of Queen Sophia, is an important monument of the Polish language.