Athelney

Your posting Formicant reminded me of this from the A/S Chronicle, out of date for prehistory but still...

AD 878 in this year at midwinter,

after Twelve Night, the host stole away to Chippenham (Wiltshire)

and overran the land of the West Saxons and occupied it.

And many of the people they drove beyond the sea

and the greater part of those that remained they harried

and the people submitted to them,

except the King Alfred.

And he with a small band, retreated through the woodlands

and into the fastness of the marshes...

After this at Easter, Alfred with a small band,

Raised a fortress at Athelney, and from it warred on the host,

With the men of that part of Somerset which was nearest to it.

Then, in the seventh week after Easter,

he rode to Egbryht's stone on the east of Selwood.......

Anglo-Saxon Chronicle

it goes on of course but its a lot to type ;)