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.