Eric XIV, 1533–77, king of Sweden (1560–68), son and successor of Gustavus I. To strengthen the power of the crown, he limited (1561) the privileges of the royal dukes. He forbade the marriage of his half-brother John, duke of Finland, to the sister of the king of Poland. When John disobeyed he was accused of treason, lost his estates, and was imprisoned (1563) with his wife. Eric feared conspiracies among the nobles, many of whom were not reconciled to a strong hereditary monarchy. He had many nobles assassinated, including Nils Sture, of the powerful Sture family. Having unsuccessfully sought the hand of Elizabeth I of England, Eric married his peasant mistress in 1568 and had her crowned queen. Reverses in Sweden's war (1563–70) with Denmark, the unpopularity of his adviser, Goran Persson, and Eric's evident insanity enabled John, who had been released, to lead an insurrection against him. Eric was deposed (1568) and died in prison. He was succeeded by John, who ruled from 1568 to 1592 as John III, and then by John's son Sigismund III of Poland. Eric, a patron of arts and letters, was himself a writer.