A devout Roman Catholic, Mary married the widower James, who was then the younger brother and heir presumptive of Charles II.

[3] Born a princess of the northwestern Italian Duchy of Modena, Mary is primarily remembered for the controversial birth of Prince James Francis Edward, her only surviving son.

It was widely rumoured that he was smuggled into the birth chamber in a warming pan in order to perpetuate her husband's Roman Catholic Stuart dynasty.

In widowhood, Mary spent time with the nuns at the Convent of Chaillot, frequently during summers with her daughter, Louisa Maria Teresa.

When James Francis Edward was asked to leave France as part of the settlement from the Treaty of Utrecht in 1713, which ended the War of the Spanish Succession (1701–1714), Mary stayed despite having no family there, her daughter having died of smallpox.

[5][6] Mary's education was excellent;[7] she spoke French and Italian fluently, had a good knowledge of Latin and, later, mastered English.

[8][9] Mary was described by contemporaries as "tall and admirably shaped", and was sought as a bride for James, Duke of York, by Lord Peterborough.

[12] Duchess Laura was not initially forthcoming with a reply to Peterborough's proposal, hoping, according to the French ambassador, for a "grander" match with the eleven-year-old Charles II of Spain.

[13][14] Whatever the reason for Laura's initial reluctance, she finally accepted the proposal on behalf of Mary, and they were married by proxy on 30 September 1673, she just shy of 15, he being 39.

[18] Parliament, which was entirely composed of Protestants, reacted poorly to the news of a Roman Catholic marriage, fearing it was a "Papist" plot against the country.

[35] Their reputation in tatters, the Yorks were reluctantly exiled to Brussels, a domain of King Charles II of Spain, ostensibly to visit Lady Mary—since 1677 the wife of Prince William III of Orange.

[36][37][38] Accompanied by her not yet three-year-old daughter Isabella and Lady Anne, the Duchess of York was saddened by James's extra-marital affair with Catherine Sedley.

[41] They feared the King's eldest illegitimate son, James Scott, 1st Duke of Monmouth, the commander of England's armed forces, might usurp the crown if Charles died before their return.

[45] The Yorks were recalled to London in February 1680, only to return again to Edinburgh that autumn; this time they went on a more honourable footing: James was created King's Commissioner to Scotland.

[46] Separated from Lady Isabella once again, Mary sank into a state of sadness, exacerbated by the passing of the Exclusion bill in the Commons.

[49] At the same time as news reached Holyrood of Isabella's death, Mary's mother was falsely accused of offering £10,000 for the murder of the King.

[55] Despite all the furore over Exclusionism, James ascended his brother's thrones easily upon the latter's death – which occurred on 6 February 1685 OS – possibly owing to the risk that the said alternative might provoke another civil war.

So much so, in fact, that the Tuscan envoy reported to Florence that "general opinion turns [for Mary's successor] in the direction of the Princess, Your Highness's daughter".

[60][61] France, too, was preparing for Mary's imminent demise, putting forward as its candidate for James's new wife the Duke of Enghien's daughter.

[69] Issued by seven leading Whig nobles, the invitation for William to invade England signalled the beginning of a revolution that culminated in James's deposition.

[76] On 9 December 1688, Mary left London in disguise with the infant Prince of Wales and in the company of Victoria Davia-Montecuculi, under the arrangement of Antoine Nompar de Caumont.

[78] James, however, backed by Louis XIV of France, still considered himself king by divine right, and maintained it was not within parliament's prerogative to depose a monarch.

[85] During James's campaign, Mary supported his cause throughout the British Isles: she sent three French supply ships to Bantry Bay and £2,000 to Jacobite rebels in Dundee.

[77] Mary tried her best to assist those of her husband's followers living in poverty, and encouraged her children to give part of their pocket money to Jacobite refugees.

[92] Queen Mary, concerned for the dynasty's future, urged the Cardinal-Duke to resign his cardinalate, "for the good of the people and for the perpetuation of the sovereign house of Este".

[104] Dressed in mourning for the remainder of her life, Mary's first act as regent was to disseminate a manifesto, outlining James Francis Edward's claims.

[108] Having wished to become a nun in her youth, Mary sought refuge from the stresses of exile at the Convent of the Visitations, Chaillot, near Paris, where she befriended Louis's penitent mistress, Louise de La Vallière.

[110] It was here, too, in 1711, that Mary found out that, as part of the embryonic Treaty of Utrecht, James Francis Edward was to lose Louis's explicit recognition and be forced to leave France.

[111] Deprived of the company of her family, Mary lived out the rest of her days at Chaillot and Saint-Germain in virtual poverty, unable to travel by her own means because all her horses had died and she could not afford to replace them.

[112] Following her death from cancer on 7 May 1718, Mary was remembered fondly by her French contemporaries, three of whom, Elizabeth Charlotte of the Palatinate, the Duke of Saint-Simon and the Marquis of Dangeau, deemed her a "saint".