During the Reign of Charles X Gustav and Charles XI
At the coronation of her brother King Charles X Gustav in 1654, Maria Euphrosyne was granted the rank and status of a Royal Princess of Sweden. This was opposed by some parts of the nobility. Maria Euphrosyne did not use the title of Countess, but was generally referred to as Princess. Maria Euphrosyne visited both her spouse and her brother in warfare: she visited her spouse in Germany and, in 1656, in Riga in Swedish Livonia, from where she had to flee again with her courtiers after just two weeks when the Russians set fire to the city. During the Dano-Swedish War (1658-1660), she and her sister-in-law Queen Hedvig Eleonora lived at Kronborg in Denmark after it had been taken by the Swedish general Carl Gustaf Wrangel. In 1658, her brother King Charles told her that he wished to make her spouse Lord High Chancellor of Sweden, but she convinced him not to by saying that Magnus Gabriel was more suited for military work. In 1660, she was present at the death bed of her brother in Gothenburg. He promised her great estates in Denmark, pensions for her children, and told her that he had named her consort Lord High Chancellor of Sweden in his will against her wish.
Maria Euphrosyne was very active as a mediator and a spokesperson for supplicants who wished to speak to her spouse or to her brother the King (and later her nephew the King) on their behalf. This matters were not only small things, they also concerned women asking her to use her contacts to acquire offices of great political importance for their male relatives. In the same fashion, she acted as a mediator between her consort and the royal house, especially when he was out of favor. At Karlberg Palace, she received her supplicants in a room with paintings of her royal brother and mother, with a door open to the room where her brother the King had slept when he was a guest in her house. Contemporaries believed she was the reason for Magnus Gabriel's successful career.
In 1676, Lisbeth Carlsdotter, a witness in the Katarina witch trials inspired by the famous Gävle-Boy, tried to implicate Maria Euphrosyne and her sister-in-law Maria Sofia for sorcery. These accusations were not taken seriously, as Carlsdotter's credibility as a witness was quickly dismissed and the entire trial was soon dissolved.
In 1680, Maria's husband lost favor with her nephew, the now-King Charles XI, after the death of Johan Göransson Gyllenstierna. She was denied an audience with her nephew without witnesses and had no success in getting her spouse in favor. After she, by using her contacts, managed to get an audience in private with the King, however, she told him that she hoped Gyllenstierna was now in Hell, and the result was that her spouse was appointed Seneschal. During the great reduction of her nephew King Charles XI in the 1680s, a lot of the property of the family was confiscated by the crown. Maria Euphrosyne was not above using her status as the aunt of the King to avoid confiscation, but she was only moderately successful: in 1685, she was allowed to keep her own personal allowance and her favorite residence, Höjentorp Castle, Västergötland, but the confiscation of her husband's property continued undisturbed. Maria Euphrosyne became a widow in 1686. This was in the middle of the reduction. The King refused to pay for the funeral of her spouse, and to stop the creditors from inventorying her own personal possessions and jewelry as well. She died at Höjentorp.
Maria Euphrosyne was described as religious. She had her German saying »Gott ist mir allés» carved at a wall at Läckö Castle, as well as at a medallion, and in 1681, she anonymously published the German language prayer book »Der geistlich-hungerigen seelen himmelisches manna». In 1682, she wrote her own autobiography.
