By 870 the whole of the north and east of England had been conquered by the Danes. In that year Eadmund, the East Anglian king, went out to battle against them, and was defeated and taken prisoner. His captors offered to spare his life and restore his kingdom to him, if he would deny Christ and reign under their orders. When he refused their offers, they tied him to a tree, shot at him with arrows, and finally cut off his head. In later days the Abbey of St. Edmund's Bury was named after the martyred king. Wessex well nigh shared the fate of the rest of the country; it was saved by the skill and wisdom of Alfred. Through all the bitter struggle the Church vigorously upheld the national cause; a bishop of Elmham fell fighting against the heathen host in East Anglia, and a bishop of Sherborne in Wessex. At last Alfred inflicted a crushing defeat upon the Danish king, Guthorm, at Edington, and as the price of peace Guthorm promised to quit Wessex and accepted Christianity. He was baptized at Wedmore, in Somerset, and a treaty was made by which England was divided into two parts. Wessex was freed from the danger of conquest, and Alfred's immediate dominions were increased, while the north and east remained under the Danes. Guthorm owned the supremacy of the West Saxon king in East Anglia; his people became Christians, and in the other Danish districts the invaders for the most part also accepted Christianity when they became settled in the land.
The Danish wars had a disastrous effect on religion, morality, and learning. The monastic congregations were scattered, and men did not care to become monks. Pure Benedictinism was as yet unknown in England, and a laxer system seems to have prevailed. This system, such as it was, now gave way altogether, and the monasteries that survived the ravages of the Danes fell into the hands of secular clergy, who enjoyed their estates without conforming to any rule, and who were generally married. The collapse of monasticism entailed the decay of learning, for the monastic schools were generally closed. Nor were the parish priests capable of supplying the place of the monks as teachers of the people. The drain of men entailed by the war made it necessary to confer the priesthood on many who were ignorant and otherwise unfit for full orders. And it is probable that the losses which the Church sustained during the war were not confined to monastic bodies, and that the clergy suffered considerably. A general decline in their character and efficiency naturally followed; and Alfred records how England had changed in this respect even within his own memory. He remembered the time when the "sacred orders were zealous in teaching and learning, and in all the services they owed to God, and how foreigners hied to this land for wisdom and lore;" but now, he says, "we should have to get them from abroad." For "there were very few on this side Humber who could understand their rituals in English, or translate a letter from Latin into English, and not many beyond Humber."