in its struggle against Mercia by the weakness of its assailant, the youngest and feeblest of the English states, as well as by an internal warfare which distracted the energies of the invaders. But Mercia had no sooner risen to supremacy among the English kingdoms than it took the work of conquest vigorously in hand. Offa tore from Wales the border-land between the Severn and the Wye; the raids of his successors carried fire and sword into the heart of the country; and an acknowledgement of the Mercian overlordship was wrested from the Welsh princes. On the fall of Mercia this overlordship passed to the West-Saxon kings, and the Laws of Howel Dda own the payment of a yearly tribute by "the prince of Aberffraw" to "the King of London." The weakness of England during her long struggle with the Danes revived the hopes of British independence; it was the co-operation of the Welsh on which the northmen reckoned in their attack on the house of Ecgberht. But with the fall of the Danelaw the British princes were again brought to submission, and when in the midst of the Confessor's reign the Welsh seized on a quarrel between the houses of Leofric and Godwine to cross the border and carry their attacks into England itself, the victories of Harold reasserted the English supremacy. Disembarking on the coast his light-armed troops he penetrated to the heart of the mountains, and the successors of the Welsh prince Gruffydd, whose head was the trophy of the campaign, swore to observe the old fealty and render the old tribute to the English Crown. [Sidenote: Wales and the Normans]