Five years later in 1647, Mary's husband inherited the titles of Prince of Orange and Stadtholder of Holland, Zeeland, Utrecht, Guelders, Overijssel and Groningen in the United Provinces of the Netherlands.

Eight days after her husband's death in 1650, Mary gave birth to a son, William III of Orange, who later became King of England, Scotland and Ireland.

Mary, who became the only guardian of her son, was not popular in the Netherlands because of her support of her brothers and her difficult relationship with her mother-in-law Amalia of Solms-Braunfels, who considered the princess young and inexperienced.

[1][2][3] She was baptized on the same day of her birth, as there were fears that the newborn princess was not in good health and might die; the ceremony was presided over by William Laud, Archbishop of Canterbury.

A prerequisite for such a union was Mary's conversion to Catholicism, but the princess, who at the request of her mother studied the basics of the Catholic religion, did not want to change her faith.

Queen Henrietta Maria was unable to attend the religious ceremony as it was a Protestant one; instead, she watched her daughter's wedding from a small gallery.

[13] From a political point of view, the marriage of Mary partially paid off in 1643, when Henrietta Maria persuaded the Dutch government to provide a ship and arms for Charles, and sent them to England.

[14] Shortly before leaving for the Netherlands, Mary was designated by her father Princess Royal,[10] thus establishing the tradition that the eldest daughter of the British sovereign might bear this title.

The younger daughters of British sovereigns were not consistently titled princesses of Great Britain and styled "Royal Highness" until the accession of George I in 1714.

In March, she participated in court celebrations of the recent alliance between France and the Netherlands, and led the entertainment that her husband arranged for the French ambassador.

On the day of his death, Parliament was convened, which proclaimed William II to be his father's heir as stadtholder and head of the army; one by one, the remaining titles of her late father-in-law were recognized for Mary's husband, and he became the new Prince of Orange.

On 13 August 1651, the Hoge Raad van Holland en Zeeland (Supreme Court) ruled that guardianship would be shared between Mary, her mother-in-law, and Frederick William, Elector of Brandenburg (whose wife, Louise Henriette was William II's eldest sister);[13] the Elector was chosen because he could act as a neutral party mediating between the two women, but also because as a possible heir he was interested in protecting the Orange family fortune, which Amalia feared Mary would squander.

[22] In general, Mary was not popular in the Netherlands, which was more sympathetic to Oliver Cromwell; the princess herself, because of such preferences of the Dutch, refused to hire them to serve her son.

After Mary secretly received her brother Charles II in 1651 (who considered himself the legitimate King of England), the Dutch government forbade her to accept any of her relatives.

In addition, when concluding a peace treaty, Cromwell insisted on the adoption of the Act of Seclusion, which prohibited Holland from electing a member of the Orange dynasty as stadtholder.

In addition, Cardinal Mazarin showed particular favour to the princess, and also circulated rumours that she was having an affair with (or had been secretly married to) Henry Jermyn, a member of her brother James of York's household.

Soon after her return, Mary learned that her mother-in-law Amalia had offered Charles II the hand of her daughter Henriette Catherine, which deeply angered the princess.

In 1658, Amalia tried to obtain the post of sole regent for her grandson, to whom Mary was also appointed by the Supreme Court, but the princess, with the support of her French relatives, thwarted the intrigues of her mother-in-law.

Her renewed status as an English princess, therefore, helped the attitude towards her in the Netherlands grow more tolerant:[21] in all the cities where Mary and her son passed through or attended solemn events, they were greeted with royal honours.

She accepted a monetary gift from Parliament, received in a letter dated 7 November, and asked for a long-promised dowry; to resolve this issue, the King appointed a commission.

[16][21] Having received this news, Queen Henrietta Maria arrived at the bedside of her dying daughter and made a last attempt to convert her to Catholicism, but Mary refused.

In 1672, after several years of confrontation with republican leaders in the Netherlands, 21-year-old William was nevertheless elected stadtholder of five provinces, starting with Holland on 4 July, and named commander-in-chief.

In 1688, with the support of English Protestants, William deposed Mary's father and with his wife was proclaimed co-ruler of England, Scotland, and Ireland.