 The fort may be of Iron Age origin, but was rebuilt and fortified as a "burh" by King Alfred, as part of his defense against Viking raids from the Bristol Channel around 878 AD.It would have been one of a chain of forts and coastal lookout posts, connected by the "Herepath", or "military road", which allowed Alfred to move his army along the coast, covering Viking movements at sea.Excavations have revealed a first phase of defence with a mortared wall fronting an earth bank from this period.