The House of VasaGeorg Starbäck in Berättelser ur Sweriges Medeltid, Tredje Bandet pp 264, 275, 278, 291–296 & 321 was a royal house that was founded in 1523 in Sweden. Its members ruled the Kingdom of Sweden from 1523 to 1654 and the Polish–Lithuanian Commonwealth from 1587 to 1668. Its agnatic line became extinct with the death of King John II Casimir Vasa in 1672.

The Vasa dynasty descended from a 14th-century Swedish noble family, tracing agnatic kinship to (), the of Tre Kronor Castle in Stockholm. Several members held high offices during the 15th century. In 1523, after the Stockholm bloodbath and the abolition of the Kalmar Union, Gustav Eriksson (Vasa) became King Gustav I of Sweden and the royal house was founded. His reign is sometimes referred to as the beginning of the modern Swedish state, which included the King's break with the Catholic Church during the Protestant Reformation and the foundation of the Church of Sweden.

However, his eldest son and successor Erik XIV of Sweden was overthrown by Gustav's younger son, King John III of Sweden. John III married a Catholic Polish-Lithuanian princess, Catherine Jagiellon, leading to the House of Vasa becoming rulers of Polish–Lithuanian Commonwealth.

Their Catholic son Sigismund III Vasa, then ruler of a short-lived Polish–Swedish union, was usurped in 1599 by John's Protestant brother King Charles IX of Sweden in the War against Sigismund. The dynasty was then split into a Protestant Swedish branch and a Catholic Polish-Lithuanian one, which contended for crowns in subsequent wars.

The involvement of the famous Protestant general and King Gustavus Adolphus of Sweden in the Thirty Years' War gave rise to the saying that he was the incarnation of "the Lion of the Midnight" (). Yet, notably, his daughter and heiress Queen Christina of Sweden (1632–1654) abdicated in 1654 after converting to Catholicism, and emigrated to Rome, where she was hosted by the Papacy. In the Commonwealth, John II Casimir Vasa abdicated in 1668. With his death, the royal House of Vasa became extinct in 1672, though the current King of Sweden, Carl XVI Gustaf, is descended from Gustav I through his paternal great-grandmother, Victoria of Baden, a descendant of Gustav I's great-great-grandson Adolphus Frederick II, Duke of Mecklenburg-Strelitz.

Kingdom of Sweden

Gustav I of Sweden

Gustav Eriksson, a son of Cecilia Månsdotter Eka and Erik Johansson Vasa, was probably born in 1496. The birth most likely took place in Rydboholm Castle, northeast of Stockholm, the manor house of the father, Erik. The newborn got his name, Gustav, from Erik's grandfather Gustav Anundsson. Since the end of the 14th century, Sweden had been a part of the Kalmar Union with Denmark and Norway. The Danish dominance in this union occasionally led to uprisings in Sweden. During Gustav's childhood, parts of the Swedish nobility has tried to make Sweden independent from the union. Gustav and his father Erik supported the party of Sten Sture the Younger, regent of Sweden from 1512, and its struggle against the Danish King Christian II. Following the battle of Brännkyrka in 1518, where Sten Sture's troops beat the Danish forces, it was decided that Sten Sture and King Christian would meet in Österhaninge for negotiations. To guarantee the safety of the king, the Swedish side sent six hostages to be kept by the Danes for as long as the negotiations lasted. However, Christian did not show up for the negotiations, violated the deal with the Swedish side, and took the hostages to Copenhagen. The six hostages were Hemming Gadh, Lars Siggesson (Sparre), Jöran Siggesson (Sparre), Olof Ryning, Bengt Nilsson (Färla) – and Gustav Eriksson.

Election as king

The election of Gustav Eriksson as a regent made many Swedish nobles, who had so far stayed loyal to King Christian, switch sides. Some noblemen, still loyal to the king, chose to leave Sweden, while others were killed. As a result, the Swedish Privy Council lost old members who were replaced by supporters of Gustav Eriksson. Most fortified cities and castles were conquered by Gustav's rebels, but the strongholds with the best defenses, including Stockholm, were still under Danish control. In 1522, after negotiations between Gustav Eriksson's faction and Lübeck, the Hanseatic city joined the war against Denmark. The winter of 1523 saw their joint forces attack the Danish and Norwegian areas of Scania, Halland, Blekinge, and Bohuslän. During this winter, Christian II was overthrown and replaced by Frederick I. The new king openly claimed the Swedish throne and had hopes Lübeck would abandon the Swedish rebels. The German city, preferring an independent Sweden to a strong Kalmar Union dominated by Denmark, took advantage of the situation and put pressure on the rebels. The city wanted privileges on future trade as well as guarantees regarding the loans they had granted the rebels. The Privy Council and Gustav Eriksson knew the support from Lübeck was absolutely crucial. As a response, the council decided to appoint Gustav Eriksson king.

The ceremonial election of Gustav as king of Sweden took place when the leading men of Sweden met in Strängnäs in June 1523. When the councilors of Sweden had chosen Gustav as king, he met with the two visiting councilors of Lübeck. The German representatives supported the appointment without hesitation and declared it an act of God. Gustav stated he had to bow to what was described as the will of God. In a meeting with the Privy Council, Gustav Eriksson announced his decision to accept. In the following ceremony, led by the deacon of Strängnäs, Laurentius Andreae, Gustav swore the royal oath. The next day, bishops and priests joined Gustav in Roggeborgen where Andreae raised the holy sacrament above a kneeling Gustav Eriksson. Flanked by the councilors of Lübeck, Gustav Eriksson was brought to Strängnäs Cathedral where the king sat down in the choir with the Swedish privy councilors on one side, and the Lübeck representatives on the other. After the hymn "Te Deum", Andreae proclaimed Gustav Eriksson king of Sweden. He was, however, still not crowned. In 1983, in remembrance of the election of Gustav as Swedish king on 6 June, that date was declared the National Day of Sweden.

Eric XIV of Sweden

Eric XIV was born at Tre Kronor on 13 December 1533. Before the age of two, he lost his mother. In 1536, his father, Gustav Vasa, married Margaret Leijonhufvud (1516–51), a Swedish noblewoman. He was crowned as Eric XIV, but was not necessarily the 14th king of Sweden named Eric. He and his brother Charles IX (1604–11) adopted regnal numbers according to Johannes Magnus's partly fictitious history of Sweden. There had, however, been at least six earlier Swedish kings with the name of Eric, as well as pretenders about whom very little is known.

In domestic politics, Eric's ambitions were strongly opposed by the Swedish nobility, including his half-brother, the later John III of Sweden (1537–92). John was the Duke of Finland and was married to a Polish-Lithuanian princess, which made him favourable in Poland-Lithuania. John pursued an expansionist policy in Livonia (present-day Estonia, Latvia, and the northern part of Lithuania) which led to contention between the brothers. In 1563, John was seized and tried for high treason by Eric's order.

In the fall of 1568, the dukes and the nobles rebelled, and Eric was dethroned. He was then imprisoned by Duke John, who took power. Eric's most trusted counsellor, Jöran Persson (1530–68), took much of the blame for the actions directed against the nobility during Eric XIV's reign and was executed shortly after John III ascended to the throne.

John III of Sweden

John further initiated peace talks with Denmark and Lübeck to end the Scandinavian Seven Years' War, but rejected the resulting Treaties of Roskilde (1568) where his envoys had accepted far-reaching Danish demands. After two more years of fighting, this war was concluded without many Swedish concessions in the Treaty of Stettin (1570). During the following years he defeated Russia in the Livonian War, and regained Narva by the Treaty of Plussa in 1583. His foreign policy was affected by his connection to the Polish-Lithuanian Commonwealth; his son Sigismund III Vasa was made king of Poland and Grand Duke of Lithuania in 1587.

In January 1569, John was recognized as king by the same riksdag that forced Eric XIV off the throne. But this recognition was not without influence from John; Duke Karl received confirmation on his dukedom without the restrictions of his power that the Arboga articles imposed. The nobility's power and rights were extended and their responsibilities lessened.

John was still concerned about his position as king as long as Eric was alive. In 1571 he ordered Erik's guards to kill him if there was any suspicion of an escape attempt. It is possible this is how Eric died in 1577.

Polish–Lithuanian Commonwealth

Sigismund III Vasa was born when his parents, John III and Catherine Jagiellon, were held prisoner by John's brother King Eric XIV, but John replaced Eric in 1568. Sweden had become Protestant, but young Sigismund was raised Catholic. His Polish-Lithuanian connection came through his mother, daughter of Sigismund I the Old, and the Jagiellonian dynasty had ruled Kingdom of Poland and Grand Duchy of Lithuania and finally the joint Polish–Lithuanian Commonwealth since 1386. Sigismund was elected King of the Polish–Lithuanian Commonwealth on 19 August 1587.

From that time his official name and title became "Sigismund III, by the grace of God, king of Poland, grand duke of Lithuania, Ruthenia, Prussia, Masovia, Samogitia, Livonia and also hereditary king of the Swedes, Goths and Wends"; after his father died in 1592, he added "hereditary king of the Swedes, Goths, and Vandals". Royal titles in Latin: Sigismundus Tertius Dei gratia rex Poloniæ, magnus dux Lithuaniæ, Russiæ, Prussiæ, Masoviæ, Samogitiæ, Livoniæque, necnon Suecorum, Gothorum Vandalorumque hæreditarius rex. English translation: Sigismund III, by the grace of God, king of Poland, grand duke of Lithuania, Ruthenia, Prussia, Masovia, Samogitia, Livonia, and also hereditary king of the Swedes, Goths and Vandals.

Opposition to Sigismund However, as was often the case with the Polish-Lithuanian electoral monarchy, the outcome was strongly contested by the "losers" and a faction of the Commonwealth's nobility backed Maximilian III, Archduke of Austria. Upon hearing of his election, King Sigismund slipped through the clutches of the Protestants in Sweden and landed in Poland on 7 October. He immediately agreed to give up several royal privileges to the Sejm (parliament) of the Commonwealth in the hope of winning over some of his enemies and settling the disputed election. Lesser Prussian Treasurer Jan Dulski proclaimed him king on behalf of the Crown Marshal Andrzej Opaliński. On 27 December, he was crowned in Wawel Cathedral in Kraków. It seemed that the issue of who would be King of Poland and Grand Duke of Lithuania had been settled when Maximilian III invaded at the head of his army to claim his crown. The hostilities did not last long as Hetman Jan Zamoyski at the head of a Polish-Lithuanian army loyal to King Sigismund met and successfully defeated the Austrian troops at the Battle of Byczyna and took Maximilian III as prisoner of war. However, at the request of Pope Sixtus V, King Sigismund III released Maximilian who surrendered his claim to the Polish-Lithuanian Commonwealth in 1589. King Sigismund also tried to maintain peace with his powerful neighbor by marrying Archduchess Anna of Austria in 1592. It was always his intention to be allied with Catholic Austria against the Protestant forces that were tearing Christendom apart.

Polish–Swedish union