Each of these "Five Boroughs" seems to have been ruled by its earl with his separate "host"; within each twelve "lawmen" administered Danish law, while a common "Thing" may have existed for the whole district.

In her attack on this powerful league AEthelflaed abandoned the older strategy of battle and raid for that of siege and fortress-building.

Advancing along the line of Trent, she fortified Tamworth and Stafford on its head-waters; when a rising in Gwent called her back to the Welsh border, her army stormed Brecknock; and its king no sooner fled for shelter to the northmen in whose aid he had risen than AEthelflaed at once closed on Derby.

Raids from Middle-England failed to draw the Lady of Mercia from her prey; and Derby was hardly her own when, turning southward, she forced the surrender of Leicester.

Nor had the brilliancy of his sister's exploits eclipsed those of the King, for the son of AElfred was a vigorous and active ruler; he had repulsed a dangerous inroad of the northmen from France, summoned no doubt by the cry of distress from their brethren in England, and had bridled East-Anglia to the south by the erection of forts at Hertford and Witham.