Battle of the Conwy 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 he was succeeded as Lord
Battle of Marton and that the Danes were initially put to flight, but at the end of the day and after "much slaughter" the Danes remained masters of the field. Among the fallen was Bishop Heahmund. It was the last of the battles known to be fought by Æthelred against the Danes that year, and the defeated King is reported to have died on 15 April 871. Whether he died in battle, or as a result of wounds suffered in battle is unclear. The site of the battle is unknown. Suggestions include the borders of the London Borough of Merton, Merton in Oxfordshire,