Æthelbald, king of Wessex (855-8 [subking], 858-60) ([858, marries stepmother Judith)

Æthelbald, king of the West Saxons (d. 860), was second of five sons of King Æthelwulf and of Osburh, who was the daughter of one of Æthelwulf's officials and herself descended from the West Saxon royal line. Starting in the 840s, Æthelbald attested his father's charters as a king's son, and in 850 he received the rank of ealdorman. In 855, when Æthelwulf went to Rome, Æthelbald was left in charge of the West Saxons, while his younger brother Æthelberht was appointed king of Kent and the south-east.

Æthelwulf was gone over twelve months, returning in 856 with a new bride, Judith, daughter of the Frankish king Charles the Bald. Asser reports (Vita Alfredi Regis, c. 12) that in Æthelwulf's absence, there was a plot to prevent his return hatched in the west of Wessex either by Æthelbald, or by Ealhstan bishop of Sherborne and Eanwulf ealdorman of Somerset, or by all three. As the king of the Franks took steps to ensure the safety of his daughter, it seems unlikely that he would have allowed her to be taken to a country in the middle of a civil war. It is more probable that Æthelbald revolted after hearing of his father's marriage to Judith, since the Frankish princess had her own royal lineage and might produce heirs more throne-worthy than he. Asser notes that to avoid civil war, Æthelwulf divided the previously united kingdom, assigning the western parts to Æthelbald and keeping the eastern parts for himself. It has been thought this meant that Æthelbald kept Wessex, while Æthelwulf displaced Æthelberht as king of Kent. But Wessex and its recent south-eastern conquests were hardly a "previously united" kingdom, and given that Æthelbald's co-conspirators are from the west of Wessex and that Asser and other sources suggest that Æthelwulf returned to rule his own kingdom, it is more likely that Æthelwulf kept central and eastern Wessex, allowing Æthelbald to rule western Wessex. The absence of coins in Æthelbald's name may also suggest that West Saxon coinage was in Æthelwulf's name until his death.

Whatever the situation between Æthelwulf's return in 856 and his death in 858, after Æthelwulf's death Æthelbald became sole king of the West Saxons, with his younger brother remaining king of Kent. Æthelbald also married Judith, his father's wife: there were political precedents, though Asser reports the move with horror. Very little is known of the rest of Æthelbald's reign: he died in 860 and was buried at Sherborne.