Alfred the Great succeeded his brother, Athelred (d.871). He is known for protecting Wessex from the Viking invasion, but never became, "king of all the English," since the Danes held most of the North and the East.
He pushed back the Viking incursions, and relieved neighboring kingdoms from the Danish threat, following his victory at the Battle of Ethandun in 878. He re-established Anglo-Saxon rule over the western half of Mercia. The introduction of Danelaw divided Mercia in half, giving control of the eastern portion to the Danes.
Asser (1969), "Life of King Alfred", in J. A. Giles, Memorials of King Alfred: being essays on the history and antiquities of England during the ninth century, the age of King Alfred, by various authors, Burt Franklin research & source works series (287), New York: Burt Franklin
Asser (1983), "Life of King Alfred", in Keynes, Simon; Lapidge, Michael, Alfred the Great: Asser's Life of King Alfred & Other Contemporary Sources, Penguin Classics, pp. 67–112
Attenborough, F.L. Tr., ed. (1922). The laws of the earliest English kings. Cambridge: Cambridge University Press.
It may be possible to confirm family relationships with Alfred by comparing test results with other carriers of his Y-chromosome or his mother's mitochondrial DNA.
Y-chromosome DNA test-takers in his direct paternal line on WikiTree: