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
Halfdan Ragnarsson led by Bagsecg, bolstering the ranks of Halfdan's army. According to the "Anglo-Saxon Chronicle", the Danes battled the West Saxons nine times, including the Battle of Ashdown on 8 January 871. However, the West Saxons could not be defeated, and Halfdan accepted a truce from Alfred, newly crowned king of Wessex. The Army retreated to the captured town of London and stayed there over the winter of 871/872. Coins minted in London during this period bear the name Halfdan, identifying him as the leader of the army. In autumn of 872 the Army returned to Northumbria to quell a revolt