At the Battle of Beran Byrig or Beranburh the West Saxons are said to have defeated the Britons at Barbury Castle hillfort near Swindon in 556 AD.

The Anglo-Saxon Chronicle entry for the year states: Her Cynric 7 Ceawlin fuhton wiþ Brettas æt Beranbyrg (This year Cynric and Ceawlin fought with the Britons at Beranbury).

Control of Barbury Castle is likely to have been important as it lies on The Ridgeway, a strategic communication route.