Viking raids increased in the early 840s on both sides of the English Channel, and in 843 Æthelwulf was defeated at Carhampton. In 850 Æthelstan defeated a Danish fleet off Sandwich in the first recorded naval battle in English history. In 851 Æthelwulf and his second son Æthelbald defeated the Vikings at the Battle of Aclea and, according to the "Anglo-Saxon Chronicle", "there made the greatest slaughter of a heathen raiding-army that we have heard tell of up to this present day, and there took the victory". Æthelwulf died in 858 and was succeeded by his oldest surviving son, Æthelbald, as king of Wessex and by his next oldest son, Æthelberht, as king of Kent. Æthelbald only survived his father by two years and Æthelberht then for the first time united Wessex and Kent into a single kingdom.