Born at Linlithgow in Dec., 1542, Mary became queen of Scotland on the death of her father only 6 days later. Mary of Guise betrothed her daughter to the French dauphin (later Francis II) and sent the girl to France in 1548 to be brought up by her powerful relatives the Guise family. In 1558, Mary and Francis were married under an agreement that would unite the crowns of Scotland and France if the union produced male issue. At the same time Mary signed a secret contract that bequeathed Scotland to France should she die without issue. The young couple was crowned in 1559, but Francis died the following year. The accession of Charles IX in France led to the fall of Mary's Guise uncles. This situation, together with the recent death of her own mother, prompted Mary to return to Scotland in 1561.
As a Frenchwoman and a Catholic, Mary faced a nation of hostile subjects, but her charm and beauty quickly won over many lords and commoners. She took as her principal counselors her illegitimate half brother James Stuart (later earl of Murray) and William Maitland, both friends of England, thus dispelling fears of a return of French interference in Scottish affairs. She also accepted the establishment of the Presbyterian Church and, under pressure from John Knox and his associates, consented to certain laws against Catholics. She refused, however, to abandon the Mass in her own chapel or to approve a law for compulsory attendance at Protestant services.
Mary's chief diplomatic project was to secure recognition as successor to the English throne, and she sought a marriage that would reinforce her claim. In 1565 she married her English Catholic cousin, Henry Stuart, Lord Darnley, whose descent from Margaret Tudor gave him a claim to the English throne almost as close as Mary's. Murray and some other Protestant nobles opposed the marriage and tried to raise a revolt, but they were defeated and fled to England.
Though infatuated with him at first, Mary soon came to dislike her husband and consistently refused his demands for the crown matrimonial (i.e., parliamentary assurance of power during her lifetime and after). Chagrined at his own lack of power and jealous of David Rizzio, an Italian musician who had become Mary's most trusted friend, Darnley joined a plot against Rizzio. In Mar., 1566, a band of nobles led by Darnley and the earl of Morton broke into Mary's apartment and murdered Rizzio, perhaps hoping that the shock would prove fatal to the pregnant queen. Mary talked Darnley over to her side, escaped to Dunbar to be joined by the earl of Bothwell and other loyal nobles, and so defeated the coup.
In June, 1566, Mary bore her son, James. According to tradition, about this time she fell in love with Bothwell, who had been consistently loyal to her. Darnley, meanwhile, had succeeded in making himself ever more unpopular, and all the royal counselors urged Mary to get rid of him. On the night of Feb. 9, 1567, the house in which Darnley was staying was blown up, and Darnley was found strangled outside. Bothwell was universally suspected of the murder, but was acquitted by a packed court. On Apr. 24, Mary was intercepted by Bothwell on her way to Edinburgh and carried off to Dunbar Castle. In the ensuing two weeks Bothwell secured a divorce from his wife, and on May 15 he and Mary were married by Protestant rites.
Aroused by outraged Protestant preachers, the Scots rebelled. Mary had lost the support of the people and the lords, first by her failure to punish the man believed to be her husband's murderer and then by the flagrant act of marrying him. She was forced to surrender to the rebels at Carberry Hill on June 15. Bothwell escaped, only to die insane in a Danish prison. Imprisoned at the castle of Lochleven, Mary abdicated in favor of her son and named Murray regent. In May, 1568, she escaped and soon accumulated a considerable force of men. However, she was defeated by Murray at Langside, near Glasgow, and she immediately fled to N England.
Elizabeth welcomed Mary to England and refused to turn her over to the Scottish government. She then persuaded both parties to present their cases before an English tribunal, first at York and then at Westminster (1568-69). At the inquiry Murray presented the famous Casket Letters, poems and letters allegedly written by Mary to Bothwell that supposedly proved her share in the plot against Darnley. Mary insisted that parts of the letters were forgeries, and the available evidence suggests that this was the case. In any event, the judgment was that the abdication and Murray's regency were legal, but that Mary's complicity in Darnley's murder was unproven (as it remains).
Mary became a prisoner of the English government, living for the next 16 years in the lenient custody of the earl of Shrewsbury and then under the stricter surveillance of Sir Amias Paulet. She schemed ceaselessly to regain her liberty and was party to a succession of plots that would have raised her to the English throne with the help of a Catholic uprising and a Spanish invasion. The uncovering of such plots, real and alleged, some involving important English nobles in schemes to murder Elizabeth, led Parliament to clamor for Mary's execution.
Elizabeth refused to take action until the discovery by Sir Francis Walsingham of a plot led by Anthony Babington. The evidence implicated Mary, and she was arrested and taken to Fotheringay Castle. At her trial Mary defended herself with eloquence and dignity, but there was no doubt of her complicity. Elizabeth hesitated to sign the death warrant, but after assurance from James in Scotland that he would not interfere, and under great pressure from Lord Burghley and her other counselors, she reluctantly consented. Mary was beheaded at Fotheringay on Feb. 8, 1587.
See biographies by T. F. Henderson (1905, repr. 1969), A. Fraser (1969, repr. 1984), and J. Guy (2004); studies by G. M. Thomson (1967), I. B. Cowan, comp. (1971), and J. Wormald (1988 and 2001).