Viking Age by a Viking leader called Bagsecg and his five earls. Aided by the Great Heathen Army (which had already overrun much of England from its base in Jorvik), Bagsecg's forces, and Halfdan's forces (through an alliance), the combined Viking forces raided much of England until 871, when they planned an invasion of Wessex. On 8 January 871, Bagsecg was killed at the Battle of Ashdown along with his earls. As a result, many of the Vikings returned to northern England, where Jorvic had become the centre of the Viking kingdom, but Alfred of Wessex managed to keep them out of
Alfred the Great 22 January. They were defeated again on 22 March at the Battle of Merton (perhaps Marden in Wiltshire or Martin in Dorset). Æthelred died shortly afterwards on 23 April. In April 871 King Æthelred died and Alfred succeeded to the throne of Wessex and the burden of its defence, even though Æthelred left two under-age sons, Æthelhelm and Æthelwold. This was in accordance with the agreement that Æthelred and Alfred had made earlier that year in an assembly at "Swinbeorg". The brothers had agreed that whichever of them outlived the other would inherit the personal property that King Æthelwulf had