Alfred blockaded the Viking ships in Devon, and with a relief fleet having been scattered by a storm, the Danes were forced to submit. The Danes withdrew to Mercia. In January 878, the Danes made a sudden attack on Chippenham, a royal stronghold in which Alfred had been staying over Christmas "and most of the people they killed, except the King Alfred, and he with a little band made his way by wood and swamp, and after Easter he made a fort at Athelney in the marshes of Somerset, and from that fort kept fighting against the foe". From his fort at Athelney, an island in the marshes near North Petherton, Alfred was able to mount a resistance campaign, rallying the local militias from Somerset, Wiltshire and Hampshire. 878 was the nadir of the history of the Anglo-Saxon kingdoms. With all the other kingdoms having fallen to the Vikings, Wessex alone was resisting.