Upon her widowhood in the Holy Roman Empire, Matilda was recalled to Normandy by her father, who arranged for her to marry Geoffrey of Anjou to form an alliance to protect his southern borders in France.

In 1139, Matilda crossed to England to take the kingdom by force, supported by her half-brother Robert, Earl of Gloucester, and her uncle David I of Scotland, while her husband, Geoffrey, focused on conquering Normandy.

Matilda was besieged at Oxford Castle by Stephen's forces that winter, but escaped at night across the frozen River Isis (Thames) to Abingdon, reputedly wearing white as camouflage in the snow.

Matilda returned to Normandy, now in the hands of her husband, in 1148, leaving their eldest son to continue the campaign in England; he was eventually declared Stephen's heir after the signing of the Treaty of Wallingford and succeeded to the throne as Henry II in 1154, forming the Angevin Empire.

[7] Her mother Matilda was the daughter of Malcolm III of Scotland and Margaret of Wessex, a member of the West Saxon royal family, and a descendant of Alfred the Great.

[15] The match was attractive to the English king: his daughter would be marrying into one of the most prestigious dynasties in Europe, reaffirming his own, slightly questionable, status as the youngest son of a new royal house, and gaining him an ally in dealing with France.

[26] Rebellions followed, accompanied by opposition from within the Church, which played an important part in administering the Empire, and this led to the formal excommunication of the Emperor by Pope Paschal II.

[29] Paschal fled when Henry and Matilda arrived with their army, and in his absence the papal envoy Maurice Bourdin crowned the couple at St Peter's Basilica, probably that Easter and certainly (again) at Pentecost.

[48] She does not appear to have expected to return to Germany, as she gave up her estates within the Empire and departed with her personal collection of jewels, her own imperial regalia, two of Henry's crowns, and the valuable relic of the Hand of St James the Apostle.

Around three hundred passengers – including Matilda's brother William Adelin and many other senior nobles – embarked one night on the White Ship to travel from Barfleur in Normandy across to England.

[66] Henry's control of Normandy had faced numerous challenges since he had conquered it in 1106, and the latest threat came from his nephew William Clito, the new count of Flanders, who enjoyed the support of the French king.

[100][nb 13] Matilda gave birth to her third son William on 22 July 1136 at Argentan, and she then operated out of the border region for the next three years, establishing her household knights on estates around the area.

[104] Stephen returned to the Duchy in 1137, where he met with Louis VI and Theobald to agree to an informal alliance against Geoffrey and Matilda, to counter the growing Angevin power in the region.

[120] Matilda also appealed to the papacy at the start of the year; her representative, Bishop Ulger, put forward her legal claim to the English throne on the grounds of her hereditary right and the oaths sworn by the barons.

[123] The following month, the Empress was invited by her stepmother, Queen Adeliza, to land at Arundel instead, and on 30 September Robert and Matilda arrived in England with a force of 140 knights.

[126] Stephen then agreed to a truce proposed by his brother, Henry of Blois; the full details of the agreement are not known, but the results were that Matilda and her household of knights were released from the siege and escorted to the south-west of England, where they were reunited with Robert of Gloucester.

[128][nb 16] After staying for a period in Robert's stronghold of Bristol, Matilda established her court in nearby Gloucester, still safely in the south-west but far enough away for her to remain independent of her half-brother.

[130] Although there had been only a few new defections to her cause, Matilda still controlled a compact block of territory stretching out from Gloucester and Bristol south into Wiltshire, west into the Welsh Marches and east through the Thames Valley as far as Oxford and Wallingford, threatening London.

[153] Despite securing the support of Geoffrey de Mandeville, who controlled the Tower of London, forces loyal to King Stephen and Queen Matilda remained close to the city and the citizens were fearful about welcoming the Empress.

[154] On 24 June, shortly before the planned coronation, the city rose up against the Empress and Geoffrey de Mandeville; Matilda and her followers fled just in time, making a chaotic retreat back to Oxford.

[199] The Empress had occupied the strategically essential Devizes Castle in 1142, maintaining her court there, but legally it still belonged to Josceline de Bohon, the bishop of Salisbury, and in late 1146 Pope Eugene III intervened to support his claims, threatening Matilda with excommunication if she did not return it.

[14] Matilda had originally cautioned against the appointment, but when the Prior of Mont St Jacques asked her for a private interview on Becket's behalf to seek her views, she provided a moderate perspective on the problem.

[220] Her tomb's epitaph included the lines "Great by birth, greater by marriage, greatest in her offspring: here lies Matilda, the daughter, wife, and mother of Henry", which became a famous phrase among her contemporaries.

[223] She was not called upon to make any major decisions, instead dealing with smaller matters and acting as the symbolic representative of her absent husband, meeting with and helping to negotiate with magnates and clergy.

[227] It further advertised her mixed Anglo-Saxon and Norman descent and her claim as her royal father's sole heir in a century in which feudal tenancies were increasingly passed on by heredity and primogeniture.

[241] It is unclear how strong Matilda's personal piety was, although contemporaries praised her lifelong preference to be buried at the monastic site of Bec rather than the grander but more worldly Rouen, and believed her to have substantial, underlying religious beliefs.

[247] She encouraged the Cistercians to build at Mortemer on a grand scale, with guest houses to accommodate a range of visitors of all ranks, and may have played a part in selecting the paintings for the monastic chapels.

[248] Contemporary chroniclers in England, France, Germany and Italy documented many aspects of Matilda's life, although the only biography of her, apparently written by Arnulf of Lisieux, has been lost.

[258] Matilda has attracted relatively little attention from modern English academics, being treated as a marginal figure in comparison to other contemporaries, particularly her rival Stephen, in contrast to the work carried out by German scholars on her time in the Empire.

[262] The treatment of Matilda by modern historians has been challenged by feminist scholars, including Fiona Tolhurst, who believe some traditional assumptions about her role and personality show gender bias.