Quote:"The army then marched against the Silures, a naturally fierce people and now full of confidence in the might of Caractacus, who by many an indecisive and many a successful battle had raised himself far above all the other generals of the Britons. Inferior in military strength, but deriving an advantage from the deceptiveness of the country, he at once shifted the war by a stratagem into the territory of the Ordovices, where, joined by all who dreaded peace with us, he resolved on a final struggle. He selected a position for the engagement in which advance and retreat alike would be difficult for our men and comparatively easy for his own, and then on some lofty hills, wherever their sides could be approached by a gentle slope, he piled up stones to serve as a rampart. A river too of varying depth was in his front, and his armed bands were drawn up before his defences. "

http://classics.mit.edu/Tacitus/annals.8.xii.html