What was really due to him was the organization of the episcopate, and the impulse which this gave to national unity.

But the movement towards unity found a sudden check in the revived strength of Mercia.

Wulfhere proved a vigorous and active ruler, and the peaceful reign of Oswiu left him free to build up again during fifteen years of rule (659-675) that Mercian overlordship over the tribes of Mid-England which had been lost at Penda's death.

He had more than his father's success.

Not only did Essex again own his supremacy, but even London fell into Mercian hands.