The Battle of Hingston Down was fought in 838 and is one of the most important recorded conflicts between Cornwall and Wessex. According to the Anglo Saxon Chronicle, a great naval force arrived among the West Welsh, the Chronicle’s term for the Cornish. The Cornish joined with this force before King Ecgberht of Wessex advanced against them at a place called Hengestdune. The Chronicle records that Ecgberht defeated both the Cornish and the Danes, putting them to flight. Most historians identify Hengestdune with Hingston Down, north east of Callington in Cornwall, although some alternative sites in Devon have been suggested. Hingston Down is a prominent granite ridge above the Tamar Valley, with wide views across south east Cornwall and into Devon. Its position made it a natural place to gather, defend, or observe movement along the river corridor. The Tamar was a frontier zone between Cornish territory and expanding West Saxon power, and the nearby river crossings would have been strategically important. A force arriving by sea could have moved through the Tamar or Lynher estuaries before gathering near this boundary. The battle took place during the long contraction of the old British kingdom of Dumnonia, which once covered much of what is now Devon and Cornwall. West Saxon expansion had pushed steadily westwards, and by the early ninth century Cornwall was under increasing pressure. Ecgberht had already campaigned in Cornwall in 815, but the ability of the Cornish to raise an army and ally with Viking forces in 838 shows that resistance remained organised and significant. The Viking alliance is one of the most important features of the battle. Viking activity was increasing around Britain during this period, and seaborne forces were becoming more involved in regional conflicts. The Cornish alliance with a naval force was probably a temporary military arrangement against Wessex rather than a permanent partnership. Even so, it shows that Cornwall was connected to the wider political and maritime world of ninth century Britain. Hingston Down also sits within a landscape shaped by later history and local tradition. Stories connected with Dupath Well near Callington preserve memories of conflict in the area, although they cannot be treated as direct evidence for the battle. The hill later became important for copper mining, with ore taken to Calstock Quay and shipped to South Wales for smelting. Its later industrial history adds another layer to a place already marked by frontier, movement, and human activity. Hingston Down is often described as the last recorded battle between the Cornish and the West Saxons. Its defeat did not erase Cornwall’s identity or local rule immediately, but it marked a major shift in power. Later Cornish rulers, including Dungarth, suggest that local authority continued under changing conditions, even as Cornwall was increasingly drawn into the orbit of Wessex. The battle remains a key moment in Cornwall’s early medieval history, bringing together resistance, alliance, frontier politics, and the struggle to control the Tamar landscape.