What type of details about Æthelred , lord of the mercians  can be gathered from the following bio?  Bio: Æthelred , lord of the mercians -lrb- or ealdorman Æthelred of mercia ; died 911 -rrb- became ruler of english mercia shortly after the death of its last king , ceolwulf ii in 879 . his rule was confined to the western half , as eastern mercia was then part of the viking-ruled danelaw . Æthelred 's ancestry is unknown . he was probably the leader of an unsuccessful mercian invasion of wales in 881 , and soon afterwards he acknowledged the lordship of king alfred the great of wessex . the alliance was cemented by the marriage of Æthelred to alfred 's daughter Æthelflæd . in 886 alfred took possession of london , which had suffered greatly from several viking occupations ; as it had traditionally been a mercian town , he handed control to Æthelred . in 892 the vikings renewed their attacks , and the following year Æthelred led an army of mercians , west saxons and welsh to victory over a viking army at the battle of buttington . he spent the next three years fighting them alongside alfred 's son , the future king edward the elder . at some time in the decade 899 to 909 , Æthelred 's health may have declined , and Æthelflæd may have become the effective ruler of mercia . after Æthelred 's death , Æthelflæd ruled as lady of the mercians until her own death in 918 . the couple 's only child , a daughter called Ælfwynn , then ruled briefly until deposed by her uncle , king edward .

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