By his father's will Charles received, by way of appanage, the Duchy of Södermanland, which included the provinces of Närke and Värmland; but he did not come into actual possession of them till after the fall of Eric and the succession to the throne of John in 1569.

[citation needed] This eventually kicked off nearly seven decades of sporadic warfare as the two lines of the divided House of Vasa both continued to attempt to remake the union between the Polish and Swedish thrones with opposing counter-claims and dynastic wars.

the dynastic outcome between the Swedish and Polish representatives of the House of Vasa exacerbated and radicalized the later actions of Europe's Catholic princes in the German states such as the Edict of Restitution of 1629.

In fact, it worsened European politics to the abandonment or prevention of settling events by diplomacy and compromise during the vast bloodletting of the Thirty Years' War.

The fear that Sigismund might re-catholicize the land alarmed the Protestant majority in Sweden—particularly the commoners and lower nobility, and Charles came forward as their champion, and also as the defender of the Vasa dynasty against foreign interference.

[2] It was due entirely to him that Sigismund as king-elect was forced to confirm the resolutions at the Uppsala Synod in 1593, thereby recognizing the fact that Sweden was essentially a Lutheran Protestant state.

He had steadily to oppose Sigismund's reactionary tendencies and directives; he had also to curb the nobility which sought to increase their power at the expense of the absent king, which he did with cruel rigor.

In 1595, the Riksdag of Söderköping elected Charles regent, and his attempt to force Klas Fleming, governor of Finland, to submit to his authority, rather than to that of the king, provoked a civil war.

[2] Charles sought to increase his power and the king attempted to manage the situation by diplomacy over several years, until fed up, Sigismund got permission from the Commonwealth's legislature to pursue the matters dividing his Swedish subjects, and invaded with a mercenary army.

In April 1597, after having subdued the Cudgel War and preparing to resist the expected invasion of Charles, Fleming died and was succeeded as governor by Arvid Stålarm the Younger.

[4] With Sigismund defeated and exiled—seen as both an outsider and a heretic by most of the Swedish nation—his formal deposition by the Riksdag of the Estates in 1599 served as both a natural vindication of Charles's actions and a retroactive legitimization of his claim to power.

[2] Four and a half years later Charles IX died at Nyköping, 30 October 1611 when he was succeeded by his seventeen-year-old son Gustavus Adolphus ; he had participated in the wars.