BEORNWULF, king of the Mercians (d. 826), deposed Ceolwulf and succeeded to his kingdom in 828. At the date of his accession the long quarrel between the see of Canterbury and the Mercian crown was still in progress. The immediate occasion of this quarrel was the seizure of the Kentish monasteries, South Minster and Reculver, by Coenwulf, though the true source of the disagreement is to be found in the jealousy of the Mercian king. Beornwulf had no desire to prolong the discord. In a synod and witenagemot held at Clevesho in 824 he vainly endeavoured to make some arrangement between the archbishop and the abbess Cwenthryth, daughter of Coenwulf, who had inherited the lands her father had seized from the archbishop. At the same meeting, as it seems, was decided a famous suit concerning the monastery at Westbury, the inheritance of Æthelric. In another council held by Beornwulf at Clevesho in the next year the archbishop and the abbess were reconciled, and their reconciliation put an end to the quarrel which, according to the record of the suit still preserved to us, had deprived the whole people of the Angles 'of primordial authority and the administration of holy baptism for the space of six years.' In this council also, as it seems, a suit was determined between the king and the Bishop of Selsey touching certain lands at Denton, in Sussex. The desire of Beornwulf to gain the support of the church may be connected with his jealousy of the rising power of Wessex. In 826 he marched against Ecgberht with a large army, and advanced as far as Ellandune, which is generally supposed to have been in the neighbourhood of Salisbury, There he was met by the West-Saxon army, after heavy losses on both sides was defeated and fled. The terrible slaughter made at Ellandune is commemorated by Henry of Huntingdon in a scrap of an old ballad preserved in his chronicle. This battle caused the general break-up of the Mercian power. During the next year the king and people of East Anglia put themselves under the protection of Ecgberht, and sought his help against Mercia. Beornwulf, however, seems to have made light of the alliance between Wessex and East Anglia. He invaded East Anglia, and began to slay the chief men of the kingdom. Encouraged by the promise of help from Ecgberht, the East Anglians fought with Beornwulf. They defeated and slew him, together with a large part of his army.
[Anglo-Sax. Chron.; Florence of Worcester; Henry of Huntingdon; Haddan and Stubbs's Councils and Ecclesiastical Documents, iii. 656-604; Kemble's Codex Dipl. i. 276-85].