fifteen feet wide,
with a square bottom. Towers of three stories were constructed from
distance to distance and united together by covered bridges, the
exterior parts of which were protected by hurdle-work. In this manner
the camp was protected not only by a double fosse, but also by a double
row of defenders, some of whom, placed on the bridges, could from this
elevated and sheltered position throw their missiles farther and with a
better aim; while the others, placed on the _vallum_, nearer to the
enemy, were protected by the bridges from the missiles which showered
down upon them. The entrances were defended by means of higher towers
and were closed with gates.

These formidable retrenchments had a double aim--to increase the
confidence of the barbarians by making them believe that they were
feared, and next to allow the number of the garrison to be reduced with
safety when they had to go far for provisions. For some days there were
no serious engagements, but slight skirmishes in the marshy plain which
extended between the two camps. The capture, however, of a few foragers
did not fail to swell the presumption of the barbarians, which was still
more increased by the arrival of Commius, although he had brought only
five hundred German cavalry.

The enemy remained for several days shut up in its impregnable position.
Caesar judged that an assault would cost too many lives; an investment
alone seemed to him opportune, but it would require a greater number of
troops.

He wrote thereupon to Trebonius to send him as soon as possible the
Thirteenth legion, which, under the command of T. Sextius, was in winter
quarters among the Bituriges, to join it with the Sixth and the
Fourteenth (which the first of these lieutenants commanded at Genabum),
and to come himself with these three legions by forced marches.

During this time he employed the numerous cavalry of the Remi, the
Lingones and the other allies, to protect the foragers and to prevent
surprises, but this daily service, as is often the case, ended by being
negligently performed. And one day the Remi, pursuing the Bellovaci with
too much ardor, fell into an ambuscade. In withdrawing they were
surrounded by foot-soldiers in the midst of whom Vertiscus, their chief,
met with his death. True to his Gaulish nature, he would not allow his
age to exempt him from commanding and mounting on horseback, although he
was hardly able to keep his seat. His death and this feeble