It was with a sound political instinct therefore that AEthelfrith marched in 613 upon Chester, the point where the kingdom of Cumbria, a kingdom which stretched from the Lune to the Dee, linked itself to the British states of what we now call Wales.

Hard by the city two thousand monks were gathered in one of those vast religious settlements which were characteristic of Celtic Christianity, and after a three days' fast a crowd of these ascetics followed the British army to the field.
AEthelfrith watched the wild gestures of the monks as they stood apart from the host with arms outstretched in prayer, and bade his men slay them in the coming fight.

"Bear they arms or no," said the King, "they war against us when they cry against us to their God," and in the surprise and rout which followed the monks were the first to fall.
With the battle of Chester Britain as a country ceased to exist.

By their victory at Deorham the West-Saxons had cut off the Britons of Dyvnaint, of our Devon, Dorset, Somerset, and Cornwall, from the general body of their race.

By AEthelfrith's victory at Chester and the reduction of southern Lancashire which followed it what remained of Britain was broken into two several parts.