In 869 the Vikings returned to East Anglia and conquered the kingdom, killing King Edmund. In December 870 they launched an attempt to conquer Wessex led by Kings Bagsecg and Halfdan. They occupied Reading on around 28 December. The town is between the Thames and Kennet rivers, and they set about building a ditch and rampart on the southern side between the two rivers. Three days after their arrival they sent out a large foraging party, which was defeated by an army of local levies under the command of Æthelwulf, Ealdorman of Berkshire, at the Battle of Englefield. After another four days, on about 4 January 871, Æthelred and Alfred brought up the main West Saxon army and joined Æthelwulf's forces for an attack on the Danes in the Battle of Reading. The West Saxons fought their way to the town, slaughtering all the Danes they found outside, but when they reached the town gate the Vikings burst out and defeated the West Saxons with a successful counter-attack. Among the dead was Æthelwulf, whose body was secretly carried off to be buried in his native Derby. According to the twelfth-century chronicler Gaimar, Æthelred and Alfred only escaped due to their better knowledge of the local terrain, which allowed them to lose their pursuers by fording the River Loddon at Twyford and going on to Whistley Green, which is around east of Reading.