Battle of Cefn Digoll
630 CE.
Shown on the map at 52.650°, -3.067°.
The Battle of Cefn Digoll, also known as the Battle of the Long Mynd, was fought in 630 at Long Mountain near Welshpool in modern-day Wales. The battle was fought between the Northumbrian army of King Edwin of Northumbria and an anti-Northumbrian alliance between King Cadwallon of Gwynedd and Penda of Mercia. The battle ended the Northumbrian domination of Gwynedd, and preceded a Welsh campaign into Northumbria, which led to Edwin's death at the Battle of Hatfield Chase.
Text from the Wikipedia article Battle of Cefn Digoll, licensed CC BY-SA 4.0.