thelfleda or Æthelflæd, d. 918, daughter
of King Alfred the Great of Wessex and wife of Æthelred,
ealdorman of Mercia. After her husband's death in 911 she reigned
alone and was known as the Lady of the Mercians. Her energetic
prosecution of resistance against the Danes and her wise
government, both before and after her husbands death, won
her the reputation as one of the most remarkable women in English
history. [The Illustrated Columbia Encyclopedia, 3rd ed., 1969]
Ethelfleda (? d. 918), daughter of King Alfred. As Lady of the Mercians, and sole ruler on her husbands death (?912), she besieged and took Derby and Leicester, and finally made the Danes acknowledge her sway. [World Wide Illustrated Encyclopedia, 1935]
Died before Father, unmarried and without issue. {Burkes Peerage} [GADD.GED]