Six months after his marriage, upon his father's death, Sigismund inherited the Swedish crown. Religious and political conflicts, however, fomented by his ambitious uncle, Duke Karl (who would later usurp his throne) delayed his coronation for two years. In 1594, Sigismund and Anna were finally crowned King and Queen of Sweden. Yet their reign was brief and deeply troubled. They were both devout Catholics, reigning over a Lutheran realm, and Duke Karl (who served as Regent during the King's protracted absences in Poland) seized every opportunity to weaken Sigismund's position, portraying him as a tyrant intent on reimposing Romish heresy and himself as the heroic defender of Protestantism. Anna, for her part, also clashed on religious grounds with Sigismund's stepmother, the firmly Lutheran Dowager Queen Gunilla.
One misfortune, however, was spared Queen Anna. She did not live to see her husband's loss of the Swedish throne, dying in childbirth some months before Sigismund was crushingly defeated by Karl at the Battle of Stångebro. She was only 25 years old. Her life and reign had been sadly brief but her son, Wladyslaw, would later become one of Poland's greatest and most popular monarchs as King Wladyslaw IV Vasa.