Æthelred, king of Wessex (865-71)
Æthelred I, king of the West Saxons (d. 871), was fourth of five sons of King Æthelwulf and Osburh, herself descended from the West Saxon royal line. Æthelred first attested his father's charters in 854 as a king's son, a title he retained through the reigns of his brothers Æthelbald and Æthelberht until he himself became king in 865.
The elevation of Æthelred, much less his younger brother Alfred, to the throne would have seemed unlikely in the 850s. In the arrangements Æthelwulf made after his return from Rome in 856, Wessex and its south-eastern conquests were divided between Æthelred's elder brothers Æthelbald and Æthelberht. On Æthelwulf's death in 858, Æthelbald took over Wessex, married Judith, his stepmother and an anointed queen of the Frankish royal line, and doubtless expected to produce heirs.
After Æthelbald's death in 860 without issue, Æthelberht joined Wessex to his existing kingship of Kent. It seems likely that Æthelred would have been expected to gain Wessex: a note in the historical preamble to King Alfred's will that part of Æthelwulf's inheritance was meant to descend among Æthelbald, Æthelred and Alfred suggests that Æthelberht was expected to set up his own cadet branch of the family in Kent, and so no longer to need estates in Wessex. However, on Æthelbald's death, Æthelred and Alfred gave up their part of that inheritance to Æthelberht on condition that he return it to them on his death. The likeliest explanation is that Æthelberht received the kingship of Wessex, and also this inheritance intended to descend to Æthelred and Alfred, because his younger brothers were too young to lead a country facing Viking attack in 860: Alfred was only eleven, Æthelred perhaps a year or so older. This explanation would neatly fit the fact that twice in 862 and 863, presumably once he had come of age, Æthelred did issue charters as king of the West Saxons (S 335 and 336). He must have done so as Æthelberht's deputy or in his absence, as there is no record of conflict between the brothers and Æthelred continued witnessing Æthelberht's charters as a king's son in 864.
After Æthelberht's death in 865, Æthelred became sole king of the West Saxons. In the same year, what the Anglo-Saxon Chronicle calls the "great heathen army" arrived in England, and completely changed the scale of the Viking attacks: within five years, these Vikings had conquered and installed their own rulers over Northumbria and East Anglia. In 868, when they took Nottingham in Mercia, the Mercian king Burgred, Æthelred's brother-in-law, asked for West Saxon help. Æthelred and Alfred led the West Saxons to Nottingham and besieged the Vikings: there was no decisive battle, but the Mercians were able to make peace with (presumably buy off) the Vikings, who returned to York.
The Vikings turned their attention to Wessex late in 870, setting up base at Reading. Æthelred and Alfred led the West Saxons against the Vikings at Reading, resulting in a large battle with great slaughter which the West Saxons lost. Four days later Æthelred and Alfred fought against the Vikings at Ashdown, and this time the West Saxons were victorious. A fortnight later they fought again at Basing, resulting in a Danish victory. Two months afterwards, at Meretun, Æthelred and Alfred again fought the Vikings, and again lost; to make things worse, after this battle another Viking army (the "great summer army") landed at Reading. Shortly after Easter in 871 (on 23 April according to John of Worcester), Æthelred died, and was buried at Wimborne.
Æthelred had two sons, Æthelhelm and Æthelwald: Æthelwald rebelled against Alfred's son Edward in 899, and was killed at the battle of the Holme in 902. The only other known descendent of Æthelred is Æthelweard, a late tenth-century ealdorman who notes his descent from Æthelred in his Chronicle.