After the death of Gustav I vasa, his three sons immediately started arguing on who would be come king.
The oldest son, Erik XIV was crowned king 1560 and reigned until he was killed 1568. He also became king of Estonia after the succesful invasion 1561.
In the early years of his reign, he started showing signs of mental instability which later developed into insanity. He also suffered from schizoefrenia. There have also been debates on whether his ‘illness’ started before or after the Sture murders, which was the murder of the former ‘royal’ family that had the greatest power in Sweden before Kristian II, also knows as the tyrant, took the power.
He was killed 1568 by aresenic poisoning and a famous tale was that he was killed by his brother, later Johan III, when Johan poisoned his pea soup.
Johan III of Sweden is mostly known for the fact that he supposedly killed his own brother. He was the second son of Gustav Vasa and was crowned king after is brother’s death. He reigned from 1568 to 1592 and led some very succesful war, for an example against Russia which gave Sweden the city of Narva.
He was married to Katerina of Jagellonica (Swedish name) and had the son Sigismund. His son was crowned king of Poland 1587 which improved the Swedish- Polish relations. 1592, his son was crowned king of Sweden.
Sigismund III Vasa of the Polish-Lithuanian commonwealth, or better known as just Sigismund in Sweden was king over Sweden between 1592 to 1599. His biggest aspiration was to make a personal union between Poland and Sweden which was of course valid during his reign (the Polish-Swedish union) . When he was desposed from the Swedish throne 1599 by his uncle, he spent the rest of his life trying to reclaim what he had lost.
Carl, or Charles, IX of Sweden was king between 1604 to his death, 1611. He was the youngets of Gustav Vasa’s three sons and Sigismund’s uncle.
His path to the throne was by countering Sigismund in more or less everything and when he was finally at the throne, he launched a massive blood bath in Linköping, also know and Linköping’s bloodbath, where he decapitated everyone that was supporting Sigismund.
The fact that Sigismund had been dethroned in Sweden and had to return to Poland started a a disagreement between the two branches of the Vasa dynasty and meant war between Poland and Sweden.