Guthrum, as recorded by the ‘Anglo-Saxon Chronicles’, appeared at the head of the Great Summer Army, who joined up with the Great Heathen Host in East Anglia in 871, the year of Alfred the Great’s accession to the throne of Wessex and known as the Year of Battles.
Guthrum’s army ranged over southern England between Reading and Cambridge for the next two years, before heading north and spending the winter of 873 at Repton, south of Derby, where they built an extensive, D-shaped defensive structure. They also had to dig a mass grave for over two hundred of their warriors who died there of disease.
The Mercian king, Burgred, was defeated in 874 and Guthrum took his army back to Cambridge. In 876, he moved on Wessex, taking up headquarters in Wareham on the Dorset coast. The fighting this year was indecisive, with Guthrum swearing an oath on his golden arm-ring to uphold a peace with Alfred. This treaty was soon broken, with Guthrum’s men marching first to Exeter and then back into Mercia, spending the winter of 877 in Gloucester.
On 5th January 878, Guthrum attacked King Alfred at his winter quarters at Chippenham, Wiltshire. Alfred fled for his life into the fens until late springtime, during which time he managed to famously burn the cakes and also raise a levy of local fighting men. These men followed him back to Chippenham, where he defeated Guthrum at the Battle of Edginton. This led to another, longer-lasting, peace treaty as well as Guthrum’s conversion to Christianity, and the formation of the Danelaw, which made the Norse presence in England permanent. Guthrum spent the next ten years establishing his English kingdom.