For ten years after the wintering in Sheppey, England was left in a state of comparative peace. The change came in 866 when a large Danish force which had been bribed to leave the Seine by Charles the Bald sailed to England and took up its quarters in East Anglia. In 867 they crossed the Humber and captured York, their task being made easier by the quarrels of Aelle and Osberht as to the kingship of Northumbria. Next year the rivals patched up their differences, but failed to recapture York from the Danes under Ívarr and Ubbi. Setting up a puppet king Ecgberht in Northumbria north of the Tyne, the Danes next received the submission of Mercia and returned to York in 869. In 870 they marched through Mercia into East Anglia, as far as Thetford, engaged the forces of Edmund, king of East Anglia, defeated and slew him, whether in actual battle or in later martyrdom, as popular tradition would have it, is uncertain. The death of St Edmund, king and martyr, soon became an event of European fame and no Viking leader was more widely execrated than the cruel Ívarr, who was deemed responsible.
The turn of Wessex came next. The fortunes of battle fluctuated but the accounts usually terminate with the ominous words 'the Danes held possession of the battle field.' In 871, Alfred commenced his heroic struggle with the Danes and in the first year of his reign some nine pitched battles were fought, beside numerous small engagements. So keen was the West Saxon resistance that a truce was made in 871 and the Danes turned their attention to Mercia once more. London was forced to ransom itself at a heavy price and a coin of Halfdanr, probably minted in London at the time, has been found. After a hurried visit to Northumbria the here settled down for the winter of 872-3 at Torksey in the Lindsey district, whence they moved in 873 to Repton in Derbyshire. They overthrew Burhred of Mercia and set up a foolish thegn of his as puppet ruler of that realm. In the winter of 874-5 the here divided forces: one part went under Halfdanr to the Tyne valley, the other under Guthrum (O.N. Guðormr) to Cambridge.
In 876 Halfdanr divided up the lands of Northumbria among his followers who soon ploughed and cultivated them. At the same time they did not forget their old occupations. Raids were made against the Picts and the Strathclyde Welsh, while Halfdanr soon became involved in the great struggle going on in Ireland at that time between Norsemen and Danes. This ultimately led to his death in 877 (v. infra, p. [58]).
In the meantime the struggle continued in Wessex. In 875 Alfred captured seven Danish ships. In 876 the southern division of the here slipped past the West Saxon fyrd and reached Wareham in Dorsetshire, but came to terms with Alfred. Though the peace was sworn with all solemnity on their sacred altar-ring, the mounted portion of the here slipped off once more and established themselves in Exeter. Their land forces were supported by a parallel movement of the fleet. At Exeter Alfred made peace with them and the here returned to Mercia. There half the land was divided up among the Danes while the southern half was left in the hands of Ceolwulf.
Alfred reached the nadir of his fortunes when the here returned to Wessex in the winter of 877-8, drove many of the inhabitants into exile across the sea, and received the submission of the rest with the exception of King Alfred and a few followers who took refuge in the Island of Athelney amid the Somersetshire marshes. Alfred soon gathered round him a force with which he was able to issue from his stronghold and ultimately to inflict a great defeat on the Danes at Edington near Westbury. They now made terms with Alfred by the peace of Wedmore, and agreed to leave Alfred's kingdom while their king Guthrum received Christian baptism. They withdrew first to Cirencester and then to East Anglia. Here they settled, portioning out the land as they had done in Northumbria and Northern Mercia. A peace was drawn up between Alfred and Guthrum of East Anglia defining the boundary between their realms. It was to run along the Thames estuary to the mouth of the Lea (a few miles east of London), then up the Lea to its source near Leighton Buzzard, then due north to Bedford, then eastwards up the Ouse to Watling St. somewhere near Fenny or Stony Stratford. From this point the boundary is left undefined, probably because the kingdoms of Alfred and Guthrum ceased to be conterminous here.
England now had peace for some twelve years. Alfred made good use of the interval in reorganising his army and strengthening the kingdom generally, so that when attacks were renewed in 892 he was much better prepared to meet them. In the autumn of that year two fleets coming from France arrived in England: one landed on the Limen (between Hythe and Romney Marsh), the other under the leadership of Hæsten (O.N. Hásteinn) at Milton in North Kent. Alfred's difficulties were increased by the fact that during the next four years the Danish settlers in Northumbria and East Anglia played a more or less actively hostile part, both by land and sea. The Danes showed all their old mobility and in a series of raids crossed England more than once—first to Buttington on the Severn (co. Montgomery), then to Chester, and on a third occasion to Bridgenorth in Shropshire. They met with a uniformly stout and well organised resistance under the leadership of Alfred, his son Edward the Elder, and his brother-in-law Aethelred of Mercia, and in the end they had to retire with no fresh acquisition of territory. For the most part they distributed themselves among the East Anglian and Northumbrian Danes, but those who had no cattle wherewith to stock their land took ship and sailed back to the Seine. There were no further attacks from abroad during Alfred's reign, but piratical raids made by the East Anglian and Northumbrian Danes caused him a good deal of trouble, and in order to meet them he definitely addressed himself to the long delayed task of equipping a fleet. The vessels were carefully designed according to Alfred's own ideas: they were larger, swifter and steadier than the Danish vessels and they soon showed their worth when more than 20 vessels with their crews were lost by the Danes in one year. It is interesting to note that these vessels were manned in part by Frisian sailors, probably because of the low ebb to which English seamanship had sunk.
When once Edward the Elder's claim to the throne was firmly established in the battle fought at 'the Holm,' somewhere in South Cambridgeshire, he commenced, with the active co-operation of his brother-in-law Aethelred, ealdorman of Mercia, the great work of strengthening the hold of the English on Southern Mercia preparatory to an attempt to reconquer the Danelagh. Chester was rebuilt in 907. In 910 a fort was built at 'Bremesbyrig,' possibly Bromesberrow in Gloucestershire. Aethelred died in the next year, but his wife Aethelflæd, the 'Lady of the Mercians,' continued his work, and forts were built at 'Scergeat,' perhaps Shrewsbury, at Bridgenorth on the Severn, at Tamworth, and at Stafford in 912. In 914 Warwick was fortified, while in 915 forts were built at Chirbury in Shropshire and Runcorn in Cheshire.
On the death of Aethelred, Edward took London and Oxford and the parts of Mercia adhering to them into his own hands. Two forts were built on the north and south sides of the Lea at Hertford in 911-12, and another at Witham on the Blackwater in Essex. Edward's work soon bore fruit, for we read that in the same year a large number of those who had been under Danish rule now made submission to the king. The Danes in the Five Boroughs became restless under the continued advance of the English, and twice in the year 913 they made raids from Leicester and Northampton as far as Hook Norton in Oxfordshire and Leighton Buzzard, while in the next year Edward, for the first time in his reign, was troubled by raiders from abroad. Coming from Brittany they sailed up the Severn, ravaged South Wales and the Archenfield district of Herefordshire, but could do nothing against the garrison of Gloucester, Hereford and other neighbouring towns, which seem already to have been fortified. They were forced to leave the district and so careful a watch did Edward keep over the coast of Somerset, Devon and Cornwall that they could make no effective landing, though they tried twice, at Porlock and at Watchet. Ultimately they took up their quarters in the islands of Flatholme and Steepholme in the Bristol Channel, but lack of food soon drove them away to Ireland in a starving condition. In the same year Edward built two forts at Buckingham, one on each side of the Ouse, and his policy again found speedy justification when Earl Thurcytel (O.N. Ðorkell) and all the chief men who 'obeyed[5]' Bedford, together with many of those who 'obeyed' Northampton submitted to him.
Everything was now ready for the great advance against the Danes. Derby fell in 917, while in the next year Leicester yielded without a struggle. Their fall was accompanied by the submission of the men of Derbyshire and Leicestershire. At the same time the inhabitants of York declared themselves ready to enter the service of Mercia. Edward fortified Bedford in 915, Maldon and Towcester in South Northamptonshire in 916. Again the Danes from Northampton and Leicester tried to break through the steadily narrowing ring of forts and they managed to get as far south as Aylesbury, while others from Huntingdon and East Anglia built a fort at Tempsford in Bedfordshire near the junction of the Ivel and the Ouse. They besieged a fort at 'Wigingamere' (unidentified) but were forced to withdraw. Edward gathered an army from the nearest garrison towns, besieged, captured, and destroyed Tempsford (915). In the autumn he captured Colchester and a Danish attempt on Maldon failed. Edward now strengthened Towcester and received the submission of Earl Thurfrith (O.N. Ðorröðr) and all the Danes in Northamptonshire as far north as the Welland. Huntingdon was occupied about the same time and the ring of forts around East Anglia brought about the submission of the whole of that district, Cambridgeshire making a separate compact on its own account. In 918 Edward built a fort just south of Stamford and soon received the submission of the Danes of South Lincolnshire, and in the same year occupied Nottingham, building a fort and garrisoning it with a mixed English and Danish force. He was now ruler of the whole of Mercia owing to the death of his sister Aethelflæd, and in 919 he fortified Thelwall in Cheshire, on the Mersey, and rebuilt the old Roman fort at Manchester. In 920 he built a second fort at Nottingham and one at Bakewell in Derbyshire. The reconquest of the Danelagh was complete and Edward now received the submission of the Scots, the Strathclyde Welsh, of Regnold (O.N. Rögnvaldr) of Northumbria, and of English, Danes and Norsemen alike. The Danish settlers accepted the sovereignty of the West Saxon king and henceforward formed part of an expanded Wessex which had consolidated its power over all England south of a line drawn roughly from the Humber to the Dee.