John III (Swedish: Johan III; 20 December 1537 – 17 November 1592) was King of Sweden from 1569 until his death. He ascended the Swedish throne after successfully rebelling against his older half-brother Erik XIV. He is mainly remembered for his attempts to close the gap between the newly established Lutheran Church of Sweden and the Catholic Church, as well as his conflict with and possible murder of his brother.
John was also, quite autonomously, the Duke of Finland from 1556 to 1563. In 1581, he assumed the title Grand Duke of Finland. His first wife was Catherine Jagiellon of the Polish–Lithuanian ruling family, and their son Sigismund eventually ascended both the Polish–Lithuanian and Swedish thrones. He ended the Northern Seven Years' War, but instead, Sweden was drawn into the 25 Years' War with Russia, where minor gains were eventually made. He worked for closer relations with Poland. John III was interested in religion and culture. During his reign, he countered the growing Lutheran tendencies of the Church of Sweden under the influence of Duke Charles, and worked for a reunion with the Catholic Church and the Pope in Rome.
John III was the son of King Gustav I of Sweden and his second wife Margaret Leijonhufvud. He was the brother of Charles IX and Magnus Vasa and half-brother of Erik XIV. He was married from 4 October 1562 to Catherine Jagiellon (1526–1583), with whom he had a daughter Anna Vasa in addition to Sigismund, and from 21 February 1585 to Gunilla Johansdotter (Bielke) (1568–1597).
John III was born at Stegeborg Castle on 20 December 1537, the son of Gustav I (Vasa) and his second wife, Margareta (Eriksdotter) Leijonhufvud. He was more than once the cause of his father's displeasure, especially when, as hereditary Duke of Finland Proper (since 27 June 1556), he sought to interfere in Livonian affairs behind King Gustav's back. Gustav had placed his son in Finland to secure Swedish territory in the eastern Baltic from a Russian threat. John also cooperated with his brother Erik, and traveled to London on his behalf to woo Queen Elizabeth I, while Erik looked after John's interests in Livonia. The marriage would have secured Swedish access to Western Europe. That mission failed, but in England John observed the reintroduction of Protestantism and the Book of Common Prayer (1559), which appealed to him as he had liturgical and theological interests.
During this time he also began a relationship with a lady-in-waiting, Karin Hansdotter, with whom he lived between 1556 and 1561, and they had four illegitimate children during these years.
When John's brother Erik XIV became king and centralized power at the expense of the nobility, the brothers soon fell out. As Duke of Finland, he opposed Erik's efforts to secure Reval and other East Baltic ports. It was only with the utmost reluctance that John could bring himself to sign the Articles of Arboga in 1561, which restricted his power. The break became open when John, against Erik's will, married Princess Catherine Jagiellon in Vilnius on 4 October 1562, the younger sister of Poland's King Sigismund II Augustus, with whom Erik was at war, and when the two brothers-in-law shortly after the wedding concluded an agreement according to which John would receive from the Polish king as a pledge seven permanent castles in Livonia in return for an advance of 120,000 daler.
Erik considered this agreement to be in direct conflict with the Articles of Arboga - which it was - and as soon as he learned of it he demanded that John give up the Livonian castles. When the Duke refused to do so, and even gave an evasive answer to the King's demand that he should declare definitely whether he would adhere to Sweden or Poland, he was summoned in April 1563 to appear in Sweden to answer the charge of treasonable designs.
When the summons was not obeyed by John, he was sentenced in June 1563 by the Estates assembled in Stockholm as guilty of treason, deprived of life, property and hereditary rights to the kingdom. To carry out the sentence, a considerable army was equipped. John, who was unprepared for battle, locked himselfup in Turku Castle, defended himself there for a few weeks with 1200 men and then surrendered on 12 August 1563, in exchange for the promise of a princely prison (the Siege of Åbo). He was taken to Sweden and imprisoned at Gripsholm Castle, accompanied by his wife. When John and his wife were brought to Gripsholm on a ship, they passed through Söderport, where the executions of 30 of John's supporters took place. John remained a prisoner for more than four years. However, conditions of his imprisonment were light, especially compared to what Erik would later experience; among other things, the couple was able to receive a large shipment of books. John, who was bookish, also spent much of his time studying and conversing with his wife. Their three children were born in captivity, in 1564 Elizabeth, called Isabella, who died at the age of two, in 1566 Sigismund and in May 1568 Anna.
During Erik's insanity in autumn 1567 (see the Sture Murders), John's release was secured in October 1567, after which negotiations were begun for the Duke's restoration to his rights.
John further initiated peace talks with Denmark–Norway and Lübeck to end the Northern Seven Years' War but rejected the resulting Treaties of Roskilde in which his envoys had accepted far-reaching Danish demands. After two more years of fighting, the war was concluded without many Swedish concessions in the Treaty of Stettin. During the following years he successfully fought Russia in the Livonian War, concluded by the Treaty of Plussa in 1583, which confirmed the Swedish reconquest of Narva. As a whole his foreign policy was affected by his connection to Poland of which country his son Sigismund III Vasa was made king in 1587.
However, Erik's actions in the first half of 1568 were likely to arouse John's fears that his newly won freedom would be taken away from him again. John therefore entered into an agreement with his brother Charles and some of the nobility for a joint rising against Erik's hated regime. This revolt began in July and spread so rapidly that by mid-September the army of the dukes was already outside Stockholm, whose gates were opened to them on 29 September 1568. An important ally was John's maternal uncle Sten Leijonhufvud, who was fatally wounded. At deathbed he was made Count of Raseborg. Erik XIV was taken prisoner, and immediately afterwards John had himself hailed as king by the city authorities and by those of the nobility and army who were gathered there. Shortly after this, John executed his brother's most trusted counsellor, Jöran Persson, whom he held largely responsible for his harsh treatment while in prison.
In January 1569, John III was recognized as king by the same Diet (Riksdag) that had forced Erik XIV from the throne. But this recognition was not without concessions on the part of John: Duke Charles was confirmed in his dukedom without the restrictions on his power imposed by the Articles of Arboga; the nobility were granted privileges which, in extending their rights and limiting their duties, represent a significant moment in the history of the nobility; and special privileges were granted to the higher nobility which consolidated and developed the distinction between the various classes of the nobility which is of such profound significance in the history of the Swedish nobility.
Although power was now in King John's hands, he did not feel secure on his throne as long as his captured half-brother was alive. Three plots were uncovered during these years to depose him: the 1569 Plot, the Mornay Plot, and the 1576 Plot. Fear of his possible release constantly worried the king and led him, as early as 1571, to order the guards, in the event of the slightest danger of an attempted rescue or the like, to assassinate the captured king. It was probably as a result of such an order that Erik's life was ended in 1577. Even if this was not the case, the fact remains that John III did not shrink from the possible murder of his half-brother and that it was not against his will if it was carried out.