By 878 the Vikings had seized eastern Mercia and nearly conquered Wessex, and Alfred was reduced to being a fugitive in the Somerset marshes, but he fought back and won the Battle of Edington. This was followed by a period of peace, and in the late 880s Alfred concluded a treaty with Guthrum, king of the East Anglian Vikings, setting the boundary between Wessex and English Mercia on the one hand, and the Danelaw on the other. A further Viking assault in the mid 890s was unsuccessful.