Evidence from the charters of the time suggests that Wulfhere came to an arrangement with the Viking Guthrum rather than remain loyal to Alfred.

Then shortly after Christmas, Guthrum carried out a surprise attack on Alfred's royal vill, at Chippenham, Wiltshire.

It says that "an estate by the River Wylye, [c] granted to Æthelwulf, was land that had been confiscated from Wulfhere and his wife, for deserting both Alfred and his country in spite of the oath which he had sworn to the king and all his leading men.

The dates when Wulfhere had his land confiscated and was replaced, as Eolderman by Æthelholm, is not known, due to the absence of datable charters from the time.

[7] However the Anglo-Saxon Chronicle for 878 says: "This year, during midwinter, after twelfth night, the [Danish] army stole away to Chippenham, and overran the land of the West-Saxons, and sat down there; and many of the people they drove beyond sea, and of the remainder the greater part they subdued and forced to obey them.

However, when Alfred reestablished control, after his victory at the Battle of Edington, Wulfhere's relationship with Guthrum may have been construed as treason.