A victory of Ecgberht at Ellandun gave all England south of Thames to the West-Saxons, and the defeat of Beornwulf spurred the men of East-Anglia to rise in a desperate revolt against Mercia.

Two great overthrows at their hands had already spent its strength when Ecgberht crossed the Thames in 828, and the realm of Penda and Offa bowed without a struggle to its conqueror.

But Ecgberht had wider aims than those of supremacy over Mercia alone.

The dream of a union of all England drew him to the north.

Northumbria was still strong; in learning and arts it stood at the head of the English race; and under a king like Eadberht it would have withstood Ecgberht as resolutely as it had withstood AEthelbald.