Gustav Vasa in the context of "Kalmar Union"

The Conquest of Stockholm (Swedish: Erövringen av Stockholm) was a battle in the Swedish War of Liberation that took place in Stockholm, Sweden on 17 June 1523. The Swedish forces had for a long time laid siege to Stockholm, which was the last Danish stronghold in Sweden. The city waited for reinforcement from Denmark, but none came.

A first attempt at negotiation began on the basis that the military forces in Stockholm would surrender to Lübeck, and that Lübeck and Danzig would compensate them for their remaining pay. Gustav Vasa refused to agree with this proposal, and the siege continued.

The Treaty of Malmö (Swedish: Malmö recess), signed on 1 September 1524, ended the Swedish War of Liberation. King Frederick I of Denmark–Norway acknowledged Gustav Vasa as the king of Sweden, who in turn renounced claims to Scania and Blekinge.

The difficult question of the control of Gotland was deferred, to be refereed by a committee of representatives from various Hanseatic League cities. Swedish troops were to continue military occupation of Ranrike until the issue was resolved. By 1532, no agreement had been reached, and Ranrike was returned to Denmark–Norway in exchange for 1,200 guilders.

The monarchy of Sweden is centred on the monarchical head of state of Sweden, by law a constitutional and hereditary monarchy with a parliamentary system. There have been kings in what now is the Kingdom of Sweden for more than a millennium. Originally an elective monarchy, it became a hereditary monarchy in the 16th century during the reign of Gustav Vasa, though virtually all monarchs before that belonged to a limited and small number of political families which are considered to be the royal dynasties of Sweden.

The official continuous count usually begins with the kings who ruled both Svealand and Götaland as one kingdom. Sweden's monarchy is amongst the oldest in the world, with a regnal list stretching back to the tenth century, starting with Eric the Victorious; the Swedish monarchy has, for the past thousand years, undergone cycles of decline and strengthening, culminating in the modern constitutional monarchy.

Swedish pre-history ends around 800 AD, when the Viking Age begins and written sources are available. During the following centuries, Sweden gradually consolidated as a single nation. The Viking Age lasted until the mid-11th century. Scandinavia was formally Christianized by 1100 AD. The period 1050 to 1350—when the Black Death struck Europe—is considered the Older Middle Ages. The period from 1350 to 1523 is considered the Younger Middle Ages. The Kalmar Union between the Scandinavian countries was established in 1397 and lasted until King Gustav Vasa ended it upon seizing power during the Swedish War of Liberation, which concluded in 1523.

The early Vasa era is a period in Swedish history that lasted between 1523–1611. It began with the reconquest of Stockholm by Gustav Vasa and his men in 1523, which was triggered by the event known as the Stockholm Bloodbath in 1520, and then was followed up by Sweden's secession from the Kalmar Union, and continued with the reign of Gustav's sons Eric XIV, John III, John's son Sigismund, and finally Gustav's youngest son Charles IX. The era was followed by a period commonly referred to as the Swedish Empire, or Stormaktstiden in Swedish, which means "Era Of Great Power".

Gustav's reign was marked by internal political and religious reforms, including the Protestant Reformation, where he converted to Protestantism and seized Catholic Church property and wealth, and unification of the provinces. At the death of Gustav in 1560, he was succeeded by his eldest son Eric. Eric was intelligent and skilled, but was in a constant strain with his brother and other noblemen. He engaged in warfare against both Denmark, Russia and Poland, but suffered periods of insanity in 1567. In 1568 he was dethroned and succeeded by his brother John.