Marie Casimire Louise de La Grange d'Arquien

Queen Marie Casimire on horseback.

Marie Casimire and her sister were the only surviving children of Henri de la Grange d'Arquien, a French nobleman. She came to Poland at the age of five years as a lady in waiting to Marie Louise Gonzaga, the French-born Queen of Poland from 1645 to 1672, wife and consort to two Polish kings — Władysław IV Vasa and later his brother (who succeeded him) John II Casimir Vasa. At the court she met John Sobieski, who arrived there in 1656, but she was first married to Jan "Sobiepan" Zamoyski in 1658, with whom she had four children, all died in infancy. Zamoyski died in 1665 and the widowed Marie Casimire eventually married Sobieski on the 14 July the same year. The couple had thirteen children together, but only four of them survived until adult age — Jakub, Aleksander, Konstanty and Teresa (who later became Kurfürstin of Bavaria and mother to Emperor Karl VII).

John Sobieski was elected King of Poland in 1674, not without the influence of his wife. As the Queen of Poland, Marie Casimire quickly became unpopular, as she supported the proposed Polish–French alliance, while at the same time striving to gain privileges for her family from the French king Louis XIV.

The Royal couple became famous for their love letters, most of which were written from 1665 to 1683, when they were parted either due to John III Sobieski's military engagements or her travels to Paris. The letters give insight not only into the authentic feelings of the loving couple, but also their reflections on contemporary issues and difficulties, as well as down-to-earth matters concerning the royal household and little day-to-day decisions made by the monarch, who often consulted his wife about them.[2] Published long after the death of both of them, they can be credited with popularizing the King's way of addressing the Queen by the very diminutive form of her first name — "Marysieńka". She is widely remembered and referred to in Poland that way.

Marie Casimire was a hard, arrogant, self-centered woman. With all their love, the king and the queen quarreled, and after the king's death, their son hurried to send his mother to a distinguished exile in Rome, where she was expected to be accepted with the same respect and prestige as Christina, Queen of Sweden, a well-known art patron and founder of the Academy of Arcadia. But Marie Casimire did not enjoy Queen Christina's virtues, neither her nobility, her intelligence, nor her intellect. She believed that her devoted support of Catholicism vis-a-vis the Turks would receive an enthusiastic reception from the church in Rome, but that the Swedish queen, who had converted from Protestantism to Catholicism, had also elevated her status in the eyes of the Vatican. Nevertheless, Marie Casimire was well received and became a music patron who was mainly patronized by Domenico Scarlatti. In his role as maestro di Capella, he composed and produced seven operas with her, as a continuation of the operas written by his father, Alessandro.

Marysieńka spent the last one and a half years of her life in France, where in January 1716 she died after rinsing the stomach administered by a doctor. The coffin was moved to the chapel of St. Eustace in the church of St. Savior in Blois. On the other hand, the heart was put in a casket in the local Jesuit church (it was later lost during the French Revolution). Then in 1717, the coffin with Marysieńka's body was buried in the Capuchin church in Warsaw, next to John III. In 1733, both bodies were transported to the Wawel Cathedral in Krakow.

Marie Casimire first married Jan "Sobiepan" Zamoyski (1627–1665) on March 3, 1658 in Warsaw. They had four children, all of whom died in infancy:

• Ludwika Maria (April 1659 – May 1659).
• Son (born and died January 1660).
• Katarzyna Barbara (5 December 1660 – December 1662).
• Daughter (May 1664 – August 1664).

Zamoyski himself died April 2, 1665. Marie Casimire remarried in July of that year to the future Jan III Sobieski. This marriage was famously happy and the couple had thirteen children, though many did not survive to adulthood:

• Jakub Ludwik Henryk (2 November 1667 – 19 December 1737), Crown Prince of Poland, married Countess Palatine Hedwig Elisabeth of Neuburg and had issue.
• Twin Daughters (9 May 1669), stillborn or died shortly after birth.
• Teresa Teofila (October 1670), was a frail child and failed to survive for more than a month.
• Adelajda Ludwika (15 October 1672 – 10 February 1677), called "Barbelune", died at the age of four.
• Maria Teresa (18 October 1673 – 7 December 1675), called "La Mannone", died at the age of two.
• Daughter (October 1674), stillborn or died shortly after birth.
• Teresa Kunegunda (4 March 1676 – 10 March 1730), married Maximilian II Emanuel, Elector of Bavaria and had issue.
• Aleksander Benedykt (6 September 1677 – 19 November 1714), died unmarried.
• Daughter (13 November 1678), stillborn or died shortly after birth.
• Konstanty Władysław (1 May 1680 – 28 February 1726), married Maria Józefa Wessel but had no issue.
• Jan (4 June 1682 – 1 January/12 April 1685), died at the age of two.
• Daughter (20 December 1684), stillborn or died shortly after birth.

• 
  Queen Marie Casimire with Children.
• 
  John III Sobieski with his family.
• 
  Marysieńka as the penitent Magdalene.
• 
  The Queen's Chinese Palace.

• Marywil and Marymont, two places named after Marysieńka.
• Wilanów Palace

Wikimedia Commons has media related to Maria Kazimiera Sobieska.

• Maria Kazimierza de la Grange d'Arquien at the Wilanow Palace Museum