1911 Encyclopædia Britannica/Æthelflaed
ÆTHELFLAED (Ethelfleda), the "Lady of the Mercians," the eldest child of Alfred the Great, was educated with her brother Edward at her father's court. As soon as she was of marriageable age (probably about A.D. 886), she was married to Æthelred, earl of Mercia to whom Alfred entrusted the control of Mercia. On the accession of her brother Edward, Æthelflaed and her husband continued to hold Mercia. In 907 they fortified Chester, and in 909 and 910 either Æthelflaed or her husband must have led the Mercian host at the battles of Tettenhall and Wednesfield (or Tettenhall-Wednesfield, if these battles are one and the same). It was probably about this time that Æthelred fell ill, and the Norwegians and Danes from Ireland unsuccessfully besieged Chester. Æthelflaed won the support of the Danes against the Norwegians, and seems also to have entered into an alliance with the Scots and the Welsh against the pagans. In 911 Æthelred died and Edward took over Middlesex and Oxfordshire. Except for this Æthelflaed's authority remained unimpaired. In 912 she fortified "Scergeat" and Bridgenorth, Tamworth and Stafford in 913, Eddisbury and Warwick in 914, Cherbury, "Weardbyrig" and Runcorn in 915. In 916 she sent an expedition against the Welsh, which advanced as far as Brecknock. In 917 Derby was captured from the Danes, and in the next year Leicester and York both submitted to her. She died in the same year at Tamworth (June 12), and was buried in St Peter's church at Gloucester. This noble queen, whose career was as distinguished as that of her father and brother, left one daughter, Ælfwyn. For some eighteen months Ælfwyn seems to have wielded her mother's authority, and then, just before the Christmas of 919, Edward took Mercia into his own hands, and Ælfwyn was "led away" into Wessex.
Æthelflaed and her husband wielded almost kingly authority, and the royal title is often given them by the chroniclers.
See The Saxon Chronicle, sub ann. (especially the Mercian register in MSS. B, C and D); Florence of Worcester: Fragments of Irish Annals (ed. O'Conor), pp. 227-237; D.N.B., s.v.