The Saxons conquered Bath following the Battle of Deorham in 577, and the border was probably established along the line of the Wansdyke to the north of the Mendip Hills. Then Cenwalh of Wessex broke through at Bradford-on-Avon in 652, and the Battle of Peonnum possibly at Penselwood in 658, advancing west through the Polden Hills to the River Parrett. In 661 the Saxons may have advanced into what is now Devon as a result of a battle fought at Postesburh, possibly Posbury near Crediton.