While Eadward bridled East-Anglia his sister AEthelflaed, in whose hands AEthelred's death left English Mercia, attacked the "Five Boroughs," a rude confederacy which had taken the place of the older Mercian kingdom. Derby represented the original Mercia on the upper Trent, Lincoln the Lindiswaras, Leicester the Middle-English, Stamford the province of the Gyrwas, Nottingham probably that of the Southumbrians. 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. On the death of AEthelflaed in 918 he came boldly to the front. Annexing Mercia to Wessex, and thus gathering the whole strength of the kingdom into his single hand, he undertook the systematic reduction of the Danelaw. South of the Middle-English and the Fens lay a tract watered by the Ouse and the Nen--originally the district of a tribe known as the South-English, and now, like the Five Boroughs of the north, grouped round the towns of Bedford, Huntingdon, and Northampton. The reduction of these was followed by that of East-Anglia; the northmen of the Fens submitted with Stamford, the Southumbrians with Nottingham. Eadward's Mercian troops had already seized Manchester; he himself was preparing to complete his conquests, when in 924 the whole of the North suddenly laid itself at his feet. Not merely Northumbria but the Scots and the Britons of Strathclyde "chose him to father and lord." [Sidenote: AEthelstan]