Queen Christina was the only child of Gustavus. She was born in 1626 and became queen in 1632 when Sweden was actively engaged in the Thirty Years War. She was educated by Bishop Johannes Matthiae who was ordered by Gustavus to bring Christina up as a boy.
As Christina was only six when she became queen on her father's untimely death at the Battle of Lutzen, a regency was created lead by Axel Oxenstierna. Sweden's participation in the Thirty Years War was effectively directed by this regency until in 1644 when Christina came of age. She had attended council meetings since the age of 14 and frequently found herself in disagreement with Oxenstierna. Her education and upbringing had made her "mannish". One contemporary wrote:
"She was naught of a child except in age and naught of a woman except in sex"
Masculine in appearance, Christina was also highly intelligent.
After the failure of her attachment to the future Charles X, she swore that she would never marry but insisted that Charles Gustav would be her successor. The nobility was opposed to this and pressurised her into getting married. She ignored them and eventually got her own way by seeming to side with the lower estates in the Diet of 1650. The nobles felt threatened by this. In October 1650, it was agreed that Charles Gustav would be Christina's successor and she and the nobility mended their relationship.
Christina and Oxenstierna clashed again over the Thirty Years War. Christina wanted concessions to be made to bring the war to a swift end. Oxenstierna wanted to retain as many of Sweden's conquered overseas territory as he was aware that Sweden had been financially stretched to the limit by the time the war was drawing to a close and these conquered territories were a way for Sweden to re-finance herself.
Christina did not remain a Lutheran. As a devotee of philosophy, she continually questioned her faith. By 1652, she had made secret contacts with the Jesuits and most probably was a Catholic by then. However, conversion to Catholicism was a crime in Lutheran Sweden and as early as August 1651, she declared her willingness to abdicate.
Christina did abdicate in June 1654 when she gave way to her nominated successor, Charles Gustav who became Charles X. There is no doubt that her religious views pushed her into abdicating; however, the crown was in a desperate financial state as a result of the Thirty Years War.
Christina left Sweden and secretly converted to Catholicism in Brussels in December 1654. This was made public in November 1655. Christina died in Rome in 1689.
"Queen Christina of Sweden". HistoryLearningSite.co.uk. 2005. Web.