At first the raids were small-scale affairs, a matter of a few boatloads of men who would return home once they had collected sufficient plunder or if the resistance they encountered was too strong. But in the 850s they began to overwinter in southern England, in Ireland and along the Seine in France, establishing bases from which they began to dominate inland areas. In early January 878 a section of the Great Army led by Guthrum crossed the frontier and caught Alfred by surprise at the royal estate at Chippenham. For 80 years England was divided between the land controlled by the kings of Wessex in the south and south-west and a Viking-controlled area in the Midlands and the north. Viking kings ruled this region until the last of them, Erik Bloodaxe, was expelled and killed in 954 and the kings of Wessex became rulers of a united England. Even so, Viking (and especially Danish) customs long persisted there and traces of Scandinavian DNA can still be found in a region that for centuries was known as the Danelaw.