"Small-scale raiding of the English kingdoms continued on and off until 865, when a much larger army landed in East Anglia with the intention of invading and conquering.

Over the next few months, according to the Anglo Saxon Chronicle, he built up his force and waged a guerrilla war against Guthrum: "Alfred: and he, with a small band, with difficulty retreated to the woods and to the fastnesses[c] of the moors.... at Easter king Alfred with a small band constructed a fortress at Athelney; and from this fortress, with that part of the men of Somerset which was nearest to it, from time to time they fought against the [viking] army.

"After a few months, Alfred called his loyal men to Egbert's Stone, and from there they travelled to Edington to fight the invaders.

Guthrum subsequently retreated with the remnants of his army to their "stronghold"; Alfred pursued and besieged him for fourteen days.

The Anglo-Saxon Chronicle records the terms of the surrender: "Then the raiding army granted him [Alfred] hostages and great oaths that they would leave his kingdom and also promised him that their king [Guthrum] would receive baptism; and they fulfilled it.

[17] Another treaty soon followed that set out the boundaries between Alfred and Guthrum's territories as well as agreements on peaceful trade, and the weregild value of its people.

[20][8][21] Guthrum appears or is mentioned in several works of fiction, including: On screen, he has been portrayed by Brian Blessed[23] in episode 4 ("King Alfred") of Churchill's People; by Michael York in the 1969 film Alfred the Great; and by Thomas W. Gabrielsson in the BBC and Netflix original television series The Last Kingdom.

He is the leader of the East Engle faction in the 2018 strategy video game Total War Saga: Thrones of Britannia.

He also appears in the 2012 grand strategy game Crusader Kings II as an unlanded, unplayable character (named Guttorm) in the 867 start date at the court of Þorfinn, the ruler of Vermaland in modern-day Sweden.