Æthelred I was King of Wessex from 865 until his death in 871. He was the fourth of five sons of King Æthelwulf of Wessex, four of whom in turn became king. Æthelred succeeded his elder brother Æthelberht and was followed by his youngest brother, Alfred the Great. Æthelred had two sons, Æthelhelm and Æthelwold, who were passed over for the kingship on their father's death because they were still infants. Alfred was succeeded by his son, Edward the Elder, and Æthelwold unsuccessfully disputed the throne with him.
Æthelred as depicted in the early-fourteenth-century Genealogical Roll of the Kings of England
Charter S 332 dated 863 of King Æthelberht. Æthelred attests second from bottom on the left as "Æthelred fil[ius] reg[is]".
Charter S 338 dated 867. Æthelred, King of the West Saxons and the Men of Kent, grants Wighelm, priest, a seat in St Martin's Church, Canterbury, together with land. Most charters only survive as copies, and this is the only original of Æthelred to survive.
Æthelwulf, King of Wessex
Æthelwulf was King of Wessex from 839 to 858. In 825, his father, King Ecgberht, defeated King Beornwulf of Mercia, ending a long Mercian dominance over Anglo-Saxon England south of the Humber. Ecgberht sent Æthelwulf with an army to Kent, where he expelled the Mercian sub-king and was himself appointed sub-king. After 830, Ecgberht maintained good relations with Mercia, and this was continued by Æthelwulf when he became king in 839, the first son to succeed his father as West Saxon king since 641.
Æthelwulf in the early fourteenth-century Genealogical Roll of the Kings of England
Depiction of Æthelwulf in the late-13th-century Genealogical Chronicle of the English Kings
Coin of King Æthelwulf: "EĐELVVLF REX", moneyer Manna, Canterbury
Charter S 316 dated 855, in which Æthelwulf granted land at Ulaham in Kent to his minister Ealdhere.