Dictionary of National Biography, 1885-1900/Beorhtwulf
BEORHTWULF or BERTULF (d. 852), king of the Mercians, succeeded Wiglaf in 839. In his days Mercia was subject to the West-Saxon king. In 851 came 350 ships of the Danes to the mouth of the Thames, crews landed and took Canterbury and London by storm. Beorhtwulf gathered all his host, and went out to battle against them. He was defeated and fled. Henry of Huntingdon adds, possibly from some old ballad, that he never rallied from the blow. He died the following year. He had, by his wife Sæthryth, a son named Beorhtferth, who in 850 slew his kinsman St. Wistan, the grandson of the two Mercian kings, Wiglaf and Ceolwulf. The descent of St. Wistan from these kings doubtless roused the jealousy of Beorhtferth, and prompted the deed of violence. Several charters of Beorhtwulf are printed in Kemble's 'Codex Dipl.' vol. ii. He was succeeded by Burhred.
[Anglo-Sax. Chron. 850; Florence, a. 850–1; Henry of Huntingdon, p. 737, M.H.B.]