The Vikings were not a major threat to Wessex during Æthelwulf's reign. In 843, he was defeated in a battle against the Vikings at Carhampton in Somerset, but he achieved a major victory at the Battle of Aclea in 851. In 853 he joined a successful Mercian expedition to Wales to restore the traditional Mercian hegemony, and in the same year his daughter Æthelswith married King Burgred of Mercia. In 855 Æthelwulf went on pilgrimage to Rome. In preparation he gave a "decimation", donating a tenth of his personal property to his subjects; he appointed his eldest surviving son Æthelbald to act as King of Wessex in his absence, and his next son Æthelberht to rule Kent and the south-east. Æthelwulf spent a year in Rome, and on his way back he married Judith, the daughter of the West Frankish king Charles the Bald.