Æthelflæd (c. 870 – 12 June 918) ruled as Lady of the Mercians in the English Midlands from 911 until her death in 918. She was the eldest child of Alfred the Great, king of the Anglo-Saxon kingdom of Wessex, and his wife Ealhswith.
Æthelflæd was born around 870 at the height of the Viking invasions of England. By 878, most of England was under Danish Viking rule – East Anglia and Northumbria having been conquered, and Mercia partitioned between the English and the Vikings – but in that year Alfred won a crucial victory at the Battle of Edington. Soon afterwards the English-controlled western half of Mercia came under the rule of Æthelred, Lord of the Mercians, who accepted Alfred's overlordship. Alfred adopted the title King of the Anglo-Saxons (previously he was titled King of the West Saxons like his predecessors) claiming to rule all Anglo-Saxon people not living in areas under Viking control. In the mid-880s, Alfred sealed the strategic alliance between the surviving English kingdoms by marrying Æthelflæd to Æthelred.