 To the south of Gloucester, it becomes the Vale of Berkeley and then the Severn Estuary.The Severn Valley was under the rule of Ceawlin of Wessex after the Battle of Deorham in 577 AD as part of The Kingdom of Hwicce.In 628 AD, Penda of Mercia's victory in the Battle of Cirencester led to his rule over the Severn Valley.