Marie Casimire Louise de La Grange d'Arquien (; 28 June 1641 – 30 January 1716), known also by the diminutive form "Marysieńka", was a French noblewoman who became the queen consort of Poland and grand duchess consort of Lithuania from 1674 to 1696 by her marriage to King and Grand Duke John III Sobieski of the Polish–Lithuanian Commonwealth. She had great influence upon the affairs of state with the approval of her spouse, and acted in effect as regent during his absence.
Early life
Marie Casimire and her sister Louise Marie were the only surviving children of Henri de la Grange, Marquis d'Arquien and his first wife, Francoise de la Chastre (1613-1648). 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. The harsh climate of Poland did not prove healthy for Marie Casimire, and she developed a persistent cough and recurring fever.
At the court, she met and fell in love with John Sobieski, who arrived there in 1656, but she was first married off to Jan "Sobiepan" Zamoyski in 1658, with whom she had four children, all of whom died in early childhood. Jan Zamoyski died on 2 April 1665 and the widowed Marie Casimire married Jan Sobieski just over three months later, on 14 July of the same year. The couple had thirteen children together, but only four of them reached adulthood— Jakub, Aleksander, Konstanty and Teresa (who later became Kurfürstin of Bavaria and mother to Emperor Karl VII).
Queen of Poland
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 simultaneously striving to gain privileges for her family from the French king Louis XIV, whom she greatly admired. Like Marie Louise Gonzaga, Marie Casimire was a strong supporter of an absolute monarchy, for which she was reviled by certain spheres of the Polish nobility. The nobility were scandalized at the queen's political meddling, believing that no foreign woman should interfere. Marie Casimire also opposed Poland's policy of religious toleration and supported the Edict of Fontainebleau.
Her influence is exemplified in an incident in 1678, when the Chancellor of Nowogrod, Mikołaj Władysław Przeździecki, came to the king as the leader of an unofficial delegation to present him with evidence that the Pac family were his enemies. According to Mikolaj Wladyslaw Prze Dziecki, "The Queen knocked on the doors until the King asked for them to be opened and then took the monarch by the hand, leading him to the side, with great force, speaking in French", which the Chancellor viewed with disgust.
In the 1670s, the king of France wished to close a treaty between France, Sweden, Poland and Turkey. The French ambassador recommended working with Marie Casimire since "only the Queen Consort of Poland can convince the King, her husband, to close a treaty". Queen Marie Casimire gave her support to this issue, and a secret treaty was signed in Jaworowo 11 June 1675, and completed by a treaty between Poland and Sweden in 1677. Her Pro-French policies were however discontinued in 1678, when France had not fulfilled the terms promised her for her services, such as making her father a Peer of France, combined with the fact that Marie Casimire became concerned with the threat of the Turks.
Queen Marie Casimire sent her lady-in-waiting and confidante Malgorzata Korowska as her political agent to the emperor in 1679 to find out his view concerning and alliance between the emperor and Poland against Turkey, and on 1 April 1683, Poland signed the military alliance with the emperor which she had supported. She also played an important role during the war against Turkey, when she was credited with having convinced her spouse to support the emperor when Vienna was attacked in 1683. The French ambassador Michelle de Mongrillon described her influence when he commented: "She could move her husband first of all, then she moved the huge, lethargic corps of the Commonwealth that is so difficult to set in motion".