Yet within a few months of this successful campaign Alfred was attacked at midwinter by the main Danish army under King Guthrum. He was apparently taken by surprise by an assault at such an unusual time of the year, and was forced to escape with his military household to the isle of Athelney among the marshes of the Parrett. The invaders harried Wiltshire and Hampshire at their leisure, and vainly thought that Wessex was at last subdued. But with the spring the English rallied: a Danish force was cut to pieces before Easter by the men of Devonshire. A few weeks later Alfred had issued from Athelney, had collected a large army in Selwood, and went out to meet the enemy in the open field. He beat them at Edington in Wiltshire, blockaded them in their great camp at Chippenham, and in fourteen days starved them into surrender. The terms were that they should give hostages, that they should depart for ever from Wessex, and that their king Guthrum should do homage to Alfred as overlord, and submit to be baptized, with thirty of his chiefs. Not only were all these conditions punctually fulfilled, but (what is more astonishing) the Danes had been so thoroughly cured of any desire to try their luck against the great king that they left him practically unmolested for fourteen years (878-892). King Guthrum settled down as a Christian sovereign in East Anglia, with the bulk of the host that had capitulated at Chippenham. Of the rest of the invaders one section established a petty kingdom in Yorkshire, but those in the Midlands were subject to no common sovereign but lived in a loose confederacy under the jarls of the "Five Boroughs" already named above. The boundary between English and Danes established by the peace of 878 is not perfectly ascertainable, but a document of a few years later, called "Alfred and Guthrum's frith," gives the border as lying from Thames northward up the Lea to its source, then across to Bedford, and then along the Ouse to Watling Street, the old Roman road from London to Chester. This gave King Alfred London and Middlesex, most of Hertfordshire and Bedfordshire, and the larger half of Mercia--lands that had never before been an integral part of Wessex, though they had some time been tributary to her kings. They were now taken inside the realm and governed by the ealdorman Æthelred, the king's son-in-law. The Mercians gladly mingled with the West Saxons, and abandoned all memories of ancient independence. Twenty years of schooling under the hand of the Dane had taught them to forget old particularism. Alfred's enlarged kingdom was far more powerful than any one of the three new Danish states which lay beyond the Lea and Watling Street: it was to be seen, ere another generation was out, that it was stronger than all three together. But Alfred was not to see the happy day when York and Lincoln, Colchester and Leicester, were to become mere shire-capitals in the realm of United England. Alfred's reforms.