It is not known when Æthelred took over following Ceolwulf's death or disappearance, but in the view of Thomas Charles-Edwards, a historian of medieval Wales, Æthelred was almost certainly "Edryd Long-Hair", the leader of a Mercian army which invaded Gwynedd in 881, and was defeated by Rhodri Mawr's sons at the Battle of the Conwy. This was described by Welsh annals as "revenge by God for Rhodri". The defeat forced Æthelred to abandon his ambitions in north Wales, but he continued to exercise overlordship over the south-eastern Welsh kingdoms of Glywysing and Gwent. According to Alfred's Welsh biographer Asser, Æthelred's "might and tyrannical behaviour" forced these kingdoms to submit to the protection of King Alfred's lordship. By 883, Æthelred had accepted Alfred's lordship. Charles-Edwards suggests that in 881–882 he tried to maintain his dominance in south-east Wales, but Alfred offered his protection to Glywysing and Gwent, and in 882–883 Æthelred accepted that West Saxon power made continued independence impossible. Charles-Edwards comments: