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.

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.

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.

[9] 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 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[when?]

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.

Though 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.

Jarl Orm, the likely ruler of Leicester at the time[9] (and who attested charters between 930 and 958[citation needed]) married his daughter Aldgyth to King Olaf later that year to cement the alliance.

The burh at Lincoln guarded the route between Wessex and York,[citation needed] and was protected from much of the Anglo-Danish fighting due to its isolated location.

The West Saxon Ealdorman Aethelnoth invaded the area around Stamford in the summer of 894, but the town was not besieged and Danish rule remained unaffected.

[15] The following burhs were not part of the Five Boroughs, but were Danish settled towns with large armies and ruled in a similar manner.

With the loss of Derby and East Anglia and the advance of King Edward, their ruler, Jarl Thurferth, and the men of Northampton and Cambridge submitted to the West Saxons in 917.

Edward returned in November 915 to the Danish-held fortress, this time taking direct control of it and building a second burh on the south bank of the River Ouse.

From here, the joint army attempted to recover the recently fallen burh at Bedford, but were severely defeated and put to flight by the English garrison.

[16] Following Danish conquest in 1016, Earl Sired succeeded to the newly created Earldom of the Five Boroughs under King Canute in 1019.