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
Alfred the Great in the following year, with varying outcomes; the places and dates of two of these battles have not been recorded. A successful skirmish at the Battle of Englefield in Berkshire on 31 December 870 was followed by a severe defeat at the siege and Battle of Reading by Ivar's brother Halfdan Ragnarsson on 5 January 871. Four days later, the Anglo-Saxons won a brilliant victory at the Battle of Ashdown on the Berkshire Downs, possibly near Compton or Aldworth. Alfred is particularly credited with the success of this last battle. The Saxons were defeated at the Battle of Basing on