The Battle of the Conwy took place in 881 between King Anarawd and his brothers of the northern Welsh Kingdom of Gwynedd and a Mercian army almost certainly led by Æthelred, Lord of the Mercians. The Welsh were victorious, and the battle ended the traditional hegemony of Mercia over north Wales and contributed to Æthelred's decision to accept the lordship of King Alfred the Great of Wessex. This united the Anglo-Saxons who were not living under Viking rule under Alfred, and was a step towards the creation of the Kingdom of England. Anarawd allied himself with the Vikings shortly after the battle, but he then abandoned this alliance to follow Æthelred in accepting Alfred's lordship.
Background
The Welsh kingdoms had been subject to Mercia since the mid seventh-century, and in 853 the Mercians received the assistance of the West Saxons to maintain their hegemony. In the 870s Mercia became subject to attacks by the Viking Great Heathen Army, and in 874 it drove out King Burgred. He was succeeded by the last independent King of Mercia, Ceolwulf II, who was presented by the Anglo-Saxon Chronicle as a puppet of the Vikings. In 877 they partitioned Mercia, taking the east for themselves and leaving the west to Ceolwulf. Gwynedd was also under attack from the Vikings, and in 877 King Rhodri Mawr was defeated and driven out. He returned the following year, but immediately came under attack from Mercia, which was still trying to maintain its hegemony in Wales. King Alfred's victory over the Vikings at the Battle of Edington in May 878 relieved the pressure on Mercia, and in the same year Mercia defeated and killed Rhodri Mawr. Ceolwulf died or was deposed in 879, and was succeeded as Lord of the Mercians by Æthelred.
The battle
In 881 the Mercians invaded Gwynedd, and they met Anarawd and his brothers, sons of Rhodri, at the Battle of the Conwy. The result was a Mercian defeat, described by Welsh annals as "revenge by God for Rhodri". In the view of Thomas Charles-Edwards, this represents the Welsh view of the conflict between the two kingdoms as a blood feud. According to a thirteenth-century collection of Welsh genealogies, the Mercian leader was called "Edryd Long-Hair", almost certainly Æthelred. This is supported by The History of Wales, published in 1697, described by Simon Keynes as "of quite uncertain authority":
Aftermath
After the Battle of the Conwy, Mercia was forced to abandon its claim to lordship over north Wales, although Æthelred continued to attempt to exercise power over the south-eastern Welsh kingdoms of Glywysing and Gwent. These kingdoms sought the lordship of Alfred the Great, according to his biographer, Asser, "driven by the military power and tryanny of Ealdorman Æthelred and the Mercians". Æthelred followed in accepting West Saxon lordship by 883. In the view of Thomas Charles Edwards: Gwynedd formed an alliance with the Vikings of Northumbria soon after the battle, and according to Asser the south-west Welsh kingdom of Dyfed and the central southern kingdom of Brycheiniog sought Alfred's lordship due to the tyranny of Gwynedd. Asser also stated that Anarawd abandoned his Viking alliance because it brought him no benefit and submitted to Alfred. In Charles-Edwards' view, this may have been because Viking raids on Gwynedd continued. Welsh annals record an attack by the 'Dark Northmen' on Gwynedd in 892.
