other historians. Richard Abels in his biography discusses both sources but does not decide between them and dates Alfred's birth as 847/849, while Patrick Wormald in his Oxford Dictionary of National Biography article dates it 848/849. Berkshire had been historically disputed between Wessex and the midland kingdom of Mercia, and as late as 844, a charter showed that it was part of Mercia, but Alfred's birth in the county is evidence that, by the late 840s, control had passed to Wessex. He was the youngest of six children. His eldest brother, Æthelstan, was old enough to be appointed sub-king of Kent in 839, almost 10 years before Alfred was born. He died in the early 850s. Alfred's next three brothers were successively kings of Wessex. Æthelbald (858–60) and Æthelberht (860–65) were also much older than Alfred, but Æthelred (865–71) was only a year or two older. Alfred's only known sister, Æthelswith, married Burgred, king of Mercia in 853. Most historians think that Osburh was the mother of all Æthelwulf's children, but some suggest that the older ones were born to an unrecorded first wife. Osburh was descended from the rulers of the Isle of Wight. She was described by Alfred's biographer Asser as "a most religious woman, noble by temperament and noble by birth". She had died by 856 when Æthelwulf married Judith, daughter of Charles the Bald, king of West Francia. In 868, Alfred married Ealhswith, daughter of the Mercian nobleman Æthelred Mucel, ealdorman of the Gaini, and his wife Eadburh, who was of royal Mercian descent. Their children were Æthelflæd, who married Æthelred, Lord of the Mercians; Edward the Elder, Alfred's successor as king; Æthelgifu, abbess of Shaftesbury; Ælfthryth, who married Baldwin, count of Flanders; and Æthelweard. Background Alfred's grandfather, Ecgberht, became king of Wessex in 802, and in the view of the historian Richard Abels, it must have seemed very unlikely to contemporaries that he would establish a lasting dynasty. For 200 years, three families had fought for the West Saxon throne, and no son had followed his father as king. No ancestor of Ecgberht had been a king of Wessex since Ceawlin in the late sixth century, but he was believed to be a paternal descendant of Cerdic, the founder of the West Saxon dynasty. This made Ecgberht an ætheling – a prince eligible for the throne. But after Ecgberht's reign, descent from Cerdic was no