, or, as the Britons would call it, traitors. We
know that in one British tribe, at least, there was a pro-Roman party.
Not long before this there had fled to Caesar in Gaul, Mandubratius,
the fugitive prince of the Trinobantes, who dwelt in Essex. His
father Immanuentius had been slain in battle by Cassivellaunus,
or Caswallon[104] (the king of their westward neighbours the
Cateuchlani), now the most powerful chieftain in Britain, and he
himself driven into exile.

E. 11.--This episode seems to have formed part of a general native
rising against the over-sea suzerainty of Divitiacus, which had
brought Caswallon to the front as the national champion. It was
Caswallon who was now in command against Caesar, and if, as is very
probable, there was any Trinobantian contingent in his army, they
may well have furnished these "prisoners." For Caesar had brought
Mandubratius with him for the express purpose of influencing the
Trinobantes, who were in fact thus induced in a few weeks to set an
example of submission to Rome, as soon as their fear of Caswallon
was removed. And meanwhile nothing is more likely than that a certain
number of ardent loyalists should leave the usurper's ranks and hasten
to greet their hereditary sovereign, so soon as ever he landed.
The later British accounts develop the transaction into an act of
wholesale treachery; Mandubratius (whose name they discover to mean
_The Black Traitor_) deserting, in the thick of a fight, to Caesar,
at the head of twenty thousand clansmen,--an absurd exaggeration which
may yet have the above-mentioned kernel of truth.

E. 12.--But whoever these "prisoners" were, their information was so
important, and in Caesar's view so trustworthy, that he proceeded to
act upon it that very night. Before even entrenching his camp, leaving
only ten cohorts and three hundred horse to guard the vessels, most of
which were at anchor on the smooth sea, he set off at the head of his
army "in the third watch," and after a forced march of twelve miles,
probably along the British trackway afterwards called Watling Street,
found himself at daybreak in touch with the enemy. The British forces
were stationed on a ridge of rising ground, at the foot of which
flowed a small stream. Napoleon considers this stream to have been the
Lesser Stour (now a paltry rivulet, dry in summer, but anciently much
larger), and the hill to have been Barham Down, the camping-ground of
so many armies throughout Britis