Establishment and rule
Viking raids began in England in the late 8th century, and were largely of the 'hit and run' sort. However, in 865 various Viking armies combined and landed in East Anglia, not to raid but to conquer the four Anglo-Saxon kingdoms of England. The annals described the combined force as the Great Heathen Army. In 871, the campaign was reinforced when the Great Summer Army arrived from Scandinavia.
In 874, following their winter stay in Repton, the Great Heathen Army drove the Mercian king into exile and conquered Mercia; the exiled Mercian king was replaced by Ceolwulf II of Mercia. According to Alfred the Great's biographer, Asser, the Vikings then split into two bands. led one band north to Northumbria. Ceolwulf II was installed as the Mercian king by the Vikings, who returned in 877 to partition Mercia. The west of the kingdom went to Ceolwulf II, whilst in the east the Five Boroughs began as the fortified burhs of five Danish armies who settled the area and introduced Danelaw, their native law and customs.
Each of the Five Boroughs was ruled as a Danish Jarldom, controlling lands around a fortified burh, which served as the centre of political power. These rulers were probably initially subject to their overlords in the Viking Kingdom of Jorvik (or York) and operated their armies sometimes independently but often in alliance with rulers of their neighbours. In addition to the Five Boroughs there were also a number of very large Danish settlements to the south, including Northampton and Bedford which existed in a similar fashion.
The Five Boroughs and the English Midlands in the early 10th century
Old Norse: Djúra-bý. Although the area was settled by Danes from 877, it was not under English threat until 913 when Lady Aethelflaed of Mercia campaigned deep into Danish territory and established a burh at nearby Tamworth. In 917 Aethelflaed launched her first offensive foray and selected the fortress at Derby as her target. At that time the local ruler had probably joined with the armies from Northampton and Leicester in a number of raids to attack Mercia. Aethelflaed took advantage of the weakened burh, and successfully assaulted the town in July 917; the whole region subsequently being annexed into English Mercia.
The Danes might well have established their military headquarters on the former Roman fort of Derventio. This 6-acre (24,000 m2) rectangular fort would have given the burh the equivalent of c. 500 hides. The Vikings had camped at nearby Repton in 874, and had abandoned it a year later after suffering significantly from disease during their stay (leading to the discovery of a grave containing 245 bodies).
One of the more formidable Danish burhs, the local ruler combined his army with that of Northampton and raided the West Saxon territories of Bedfordshire and Oxfordshire in 913, and defied King Edward the Elder to besiege the West Saxon burh of Hertford. This provoked Aethelflaed to move her armies up to the fringes of Danish occupied territory around Leicester in 914 and to construct a burh at Warwick. In July 917, as part of a three-pronged assault, the combined forces of Leicester and Northampton, and possibly Derby, laid siege to the Mercian burh at Towcester. Isolated by the loss of Derby and Northampton later that year, the Mercian army returned in early 918 to ravage the local countryside, and as a result the fortress surrendered peacefully to Aethelflaed's troops.
Relieved of English rule by King Olaf of York in 941, King Edmund I besieged the Viking army at Leicester the same year. Olaf and his advisor Wulfstan I, Archbishop of York, both escaped and the siege was lifted after a peace negotiation ceded the Five Boroughs to the Kingdom of York. Jarl Orm, the likely ruler of Leicester at the time (and who attested charters between 930 and 958) married his daughter to King Olaf later that year to cement the alliance. The burh might have made use of the walls of the Roman Leicester (Ratae Corieltauvorum), of approx 7,800 ft (2,400 m) (c. 1900 hides).
The burh at Lincoln guarded the route between Wessex and York, and was protected from much of the Anglo-Danish fighting due to its isolated location. The Lincoln Danes settled the area formerly occupied by the Anglo-Saxon Kingdom of Lindsey, where the Vikings had previously overwintered in the nearby fortress of Torksey in Lindsey from 873 to 874. Lincoln probably surrendered in 918 following the capitulation of all the Danish territories on the border of Mercia and Wessex. As a former Roman legionary town, the burh probably based its walls on the old fortress of 41 acres (c.1300 hides).
The Viking army under Ivar the Boneless and first occupied Nottingham in 868 and subsequently set up winter quarters there. Burgred and his West Saxon allies laid siege, but made peace and allowed the Vikings to retreat after little serious fighting in 869. Danish reoccupation and settlement began in 877, and lasted until the assault by Edward of Wessex in the summer of 918. Edward constructed a second burh on the opposite side of the Trent in 920 to further fortify the area from Danish attack. Saxon Nottingham was known to have covered about 39 acres, which may have put the burh at c. 1300 hides.
The area around Stamford was invaded by West Saxon Ealdorman Aethelnoth in the summer of 894, but the town was not besieged and Danish rule was unaffected. The end came when King Edward assaulted Stamford in late May 918 which soon fell to the army of Wessex. Later that year Edward built a second burh on the south side of the River Welland. From Roffe, the ramparts of the northern burh might have been of approx 3100 ft (c. 750 hides), and the Edwardian burh of around 2700 ft (c. 650 hides).