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
Ailill mac Dúnlainge (died 871) his camp was attacked by the Laigin who were at first successful, but in a counter-attack they were put to flight. Ailill's name is not connected with these events which state that Muiredach mac Brain was the King of Leinster who fought the forces of Cerball. The "Fragmentary Annals" give a lengthy account of this event and state that Cerball met up with the high king's forces at Belach Gabrán (the pass of Gowran in east-central Osraighe) but both forces then retired and the hostages of the Laigin were not taken. In 871 Ailill was killed by the Vikings of