Æthelred played a major role in fighting off renewed Viking attacks in the 890s, together with Æthelflæd's brother, the future King Edward the Elder.

She was praised by Anglo-Norman chroniclers such as William of Malmesbury, who described her as "a powerful accession to [Edward's] party, the delight of his subjects, the dread of his enemies, a woman of enlarged soul".

Mercia was the dominant kingdom in southern England in the eighth century and maintained its position until it suffered a decisive defeat by Wessex at the Battle of Ellendun in 825.

His successor as the ruler of the English western half of Mercia, Æthelflæd's husband Æthelred, is first seen in 881 when, according to the historian of medieval Wales, Thomas Charles-Edwards, he led an unsuccessful Mercian invasion of the north Welsh Kingdom of Gwynedd.

[7] The most important source for history in this period is the Anglo-Saxon Chronicle but Æthelflæd is almost ignored in the standard West Saxon version, in what F. T. Wainwright calls "a conspiracy of silence".

[12] Æthelflæd was born around 870, the oldest child of King Alfred the Great and his Mercian wife, Ealhswith, who was a daughter of Æthelred Mucel, ealdorman of the Gaini, one of the tribes of Mercia.

Æthelstan, the eldest son of Edward the Elder and future king of England, was brought up in their court and, in the view of Martin Ryan, certainly joined their campaigns against the Vikings.

[24] Worcester was able to preserve considerable intellectual and liturgical continuity and, with Gloucester, became the centre of a Mercian revival under Æthelred and Æthelflæd that extended into the more unstable areas of Staffordshire and Cheshire.

[26] In 901 Æthelflæd and Æthelred gave land and a golden chalice weighing thirty mancuses to the shrine of Saint Mildburg at Much Wenlock church.

[27] At the end of the ninth century, Æthelred and Æthelflæd fortified Worcester, with the permission of King Alfred and at the request of Bishop Werferth, described in the charter as "their friend".

[29] Æthelred's health probably declined several years before his death in 911, with the result that Æthelflæd became the de facto ruler of Mercia,[30] perhaps as early as 902,[31] although he witnessed charters at a meeting attended by the king in 903.

Æthelflæd was probably responsible for restoriation of the town's Roman defences by running walls from the north-west and south-east corners of the fort to the River Dee.

Most historians date the attack on Chester to 907, but Matthew Firth argues that 910 is more likely and that it may have been part of the invasion which ended in Viking defeat at the Battle of Tettenhall.

[36] After Æthelflæd's death, Edward encountered fierce resistance to his efforts to consolidate his control of the north-west and he died there in 924, shortly after suppressing a local rebellion.

[13] In the late ninth century Gloucester had become a burh with a street plan similar to Winchester, and Æthelred and Æthelflæd had repaired its ancient Roman defences.

[42] Simon Keynes describes the town as "the main seat of their power" and Carolyn Heighway believes that the foundation of the church was probably a family and dynastic enterprise, encouraged by Alfred and supported by Edward and Bishop Werferth.

[43][44] Heighway and Michael Hare wrote: In the age when English scholarship and religion reached their lowest ebb, Mercia and in particular the lower Severn valley seem to have maintained traditional standards of learning.

[51] Alfred had constructed a network of fortified burhs in Wessex, and Edward and Æthelflæd now embarked on a programme of extending them to consolidate their defences and provide bases for attacks on the Vikings.

[62] Æthelflæd died at Tamworth on 12 June 918 and her body was carried 75 miles (121 km) to Gloucester, where she was buried with her husband in their foundation, St Oswald's Minster.

[70][71] She was also praised by Anglo-Norman historians such as John of Worcester and William of Malmesbury, who described her as "a powerful accession to [Edward's] party, the delight of his subjects, the dread of his enemies, a woman of enlarged soul".

In the Handbook of British Chronology, David Dumville refers to "Q. Æthelflæd" and comments, "The titles given her by all sources (hlæfdige, regina) imply that she wielded royal power and authority".

Stafford argues that Æthelred and Æthelflæd exercised most or all of the powers of a monarch after Alfred's death but it would have been a provocative act formally to claim regality, especially after Æthelwold's rebellion.

[78]Wainwright sees Æthelflæd as willingly accepting a subordinate role in a partnership with her brother and agreeing to his plan of unification of Wessex and Mercia under his rule.

Wainwright argues that he probably sent his oldest son Æthelstan to be brought up in Mercia, to make him more acceptable to the Mercians as king; Æthelflæd does not appear to have tried to find a husband for her daughter, who must have been nearly thirty by 918.

[79] In Wainwright's view, she was ignored in West Saxon sources for fear that recognition of her achievements would encourage Mercian separatism: [Æthelflæd] played a vital role in England in the first quarter of the tenth century.

In Keynes's view, "the conclusion seems inescapable that the Alfredian polity of the kingship 'of the Anglo-Saxons' persisted in the first quarter of the tenth century, and that the Mercians were thus under Edward's rule from the beginning of his reign".

[65] In Higham's view, Keynes makes a strong case that Edward ruled over an Anglo-Saxon state with a developing administrative and ideological unity but that Æthelflæd and Æthelred did much to encourage a separate Mercian identity, such as establishing cults of Mercian saints at their new burhs, as well as reverence for their great Northumbrian royal saint at Gloucester: There must remain some doubt as to the extent to which Edward's intentions for the future were shared in all respects by his sister and brother-in-law, and one is left to wonder what might have occurred had their sole offspring been male rather than female.

Celtic visions of Æthelred and Æthelflæd as king and queen certainly offer a different, and equally valid, contemporary take on the complex politics of this transition to a new English state.

[82] In June 2018, Æthelflæd's funeral was re-enacted in front of a crowd of 10,000 people in Gloucester, as part of a series of living history events marking the 1,100th anniversary of her death.

[83] The 1,100th anniversary of the death of Æthelflaed was marked throughout 2018 in Tamworth with a number of major events, including the unveiling of a new six-metre statue,[84] the creation of the town's biggest ever piece of community art,[85] a major commemorative church service, talks, a special guided walk, commemorative ale and an academic conference weekend drawing academics and delegates from all over the world.