That the conversion of the English to Christianity had anything to do with their slackening from the work of conquest it would be wrong to assert. Though their wars with the Welsh were not conducted with such ferocious cruelty as of old, and though (as the laws of Ine show) the Celtic inhabitants of newly-won districts were no longer exterminated, but received as the king's subjects, yet the hatred between Welsh and English did not cease because both were now Christians. The westward advance of the invaders would have continued, if only there had remained to attract them lands as desirable as those they had already won. But the mountains of Wales and the moors of Cornwall and Cumbria did not greatly tempt the settler. Moreover, the English states, which had seldom turned their swords against each other in the 5th or the 6th centuries, were engaged during the 7th and the 8th in those endless struggles for supremacy which seem so purposeless, because the hegemony which a king of energy and genius won for his kingdom always disappeared with his death. The "Bretwaldaship," as the English seem to have called it, was the most ephemeral of dignities. This was but natural: conquest can only be enforced by the extermination of the conquered, or by their consent to amalgamate with the conquerors, or by the garrisoning of the land that has been subdued by settlers or by military posts. None of these courses were possible to a king of the 7th or 8th centuries: even in their heathen days the English were not wont to massacre their beaten kinsmen as they massacred the unfortunate Celt. After their conversion to Christianity the idea of exterminating other English tribes grew even more impossible. On the other hand, local particularism was so strong that the conquered would not, at first, consent to give up their natural independence and merge themselves in the victors. Such amalgamations became possible after a time, when many of the local royal lines died out, and unifying influences, of which a common Christianity was the most powerful, sapped the strength of tribal pride. But it is not till the 9th century that we find this phenomenon growing general. A kingdom like Kent or East Anglia, even after long subjection to a powerful overlord, rose and reasserted its independence immediately on hearing of his death. His successor had to attempt a new conquest, if he felt himself strong enough. To garrison a district that had been overrun was impossible: the military force of an English king consisted of his military household of _gesiths_, backed by the general levy of the tribe. The strength of Mercia or Northumbria might be mustered for a single battle, but could not supply a standing army to hold down the vanquished. The victorious king had to be content with tribute and obedience, which would cease when he died, or was beaten by a competitor for the position of Bretwalda. Supremacy of Northumbria. Supremacy of Mercia.