In 855–856 Æthelwulf went on pilgrimage to Rome and his eldest surviving son Æthelbald took advantage of his absence to seize his father's throne. On his return, Æthelwulf agreed to divide the kingdom with his son to avoid bloodshed, ruling the new territories in the east while Æthelbald held the old heartland in the west. Æthelwulf was succeeded by each of his four surviving sons ruling one after another: the rebellious Æthelbald, then Æthelbert, who had previously inherited the eastern territories from his father and who reunited the kingdom on Æthelbald's death, then Æthelred, and finally Alfred the Great. This occurred because the first two brothers died in wars with the Danes without issue, while Æthelred's sons were too young to rule when their father died.