1520 (MDXX) was a leap year that began on a Sunday in the Julian calendar.
New Year - Kristian II's army breaks into Västergötland again under the command of Otto Krumpen.
January 19 - The Swedes are defeated by the Danes in the battle of Åsunden's ice at Bogesund (now Ulricehamn) whereby the head of state Sten Sture the younger is fatally wounded. He is taken to Stockholm, to continue the fight against the Danes from there.
February 3 - Sten Sture dies on the ice of Lake Mälaren from his injuries.
Sten's troops retreat to Tiveden, so the Danish army can continue unhindered to Västerås.
March 6 - The Swedish council aristocrats conclude a truce with the Danes with the daily assembly in Uppsala. Here, Christian II is recognized as King of Sweden since he has promised full amnesty and returned conquered castles. The castle of Sture followers is conquered and plundered. Kristian takes Stegeborg and Västerås fortresses.
March 29 - The Swedes are defeated by the Danes in the battle of Badelundaåsen.
April 6 - The Swedes are defeated by the Danes in the Good Friday battle at Uppsala.
May 31 - Gustav Eriksson (Vaasa) returns to Sweden from Lübeck and disembarks at Stensö cape outside Kalmar (which is besieged by the Danes).
June 7–24 - The meeting in the Golden Brocade Camp takes place between Henry VIII of England and Francis I of France.
September 5 - The Swedes and Danes finally agree that everything should be forgotten, all prisoners and insurgents should be released and given amnesty. Kristina Nilsdotter (Gyllenstierna) will lend Hörningsholm and the whole of Muskö; she is also promised Hämeenlinna Castle in Finland. Thus, the city of Stockholm and the castle have capitulated to the Danes, with the Stockholm Day Assembly.
September 7 - Christian II enters Stockholm. All the church bells ring and you breathe out, it's peace.
October - Christian II causes the Swedish royal crown to be inherited within his family. He also reinstates Gustav Trolle as Swedish archbishop.
November 1 - Christian II is elected King of Sweden.
November 4 - Christian II is crowned King of Sweden by the reinstated Archbishop Gustav Trolle, in which several people, including Sören Norby, Berend von Mehlen and Otto Krumpen, are dubbed knights.
November 7 - On the third day of the festivities, they come to an abrupt end and those who were involved in deposing Gustav Trolle are investigated despite the amnesty. They are sentenced to death by beheading.
November 8-10 - At least 82 people are executed on Stortorget in Stockholm in what has gone down in history as Stockholm's massacre. Bishop Hans Brask manages to escape execution through the famous bonfire, but among those executed are, among others, Gustav Vasa's father Erik Johansson. When you then burn the corpses, you also dig up the corpse of the deceased head of state Sten Sture the younger and burn it as well.
November 25 - Gustav Vasa escapes to Dalarna and encounters various adventures.
Gustav Vasa speaks to the valley men in Mora who, however, do not listen to him why he is fleeing to Norway.
Klas Kyle initiates an uprising against the Danes in Småland, which, however, is soon put down.
May - Per Brahe d.ä., Swedish count and councilor, riksdrots 1569–1590.
August 10 - Madeleine of Valois, Queen of Scotland 1537 (married to James V)
October 7 - Alessandro Farnese, Italian cardinal.
December 10 - Dorotea of Oldenburg, daughter of Christian II.
Andreas Laurentii Björnram, Swedish Archbishop 1583–1591.
February 3 - Sten Sture the younger, Swedish head of state since 1512.
February 7 - Alfonsina Orsini, Florentine regent.
April 6 - Raffaello Sanzio, Italian artist and architect.
April 11 - Agostino Chigi, Italian banker.
December 16 - Hemming G