Britons, who were their allies, sent ships to their assistance; so that
their united force amounted to 220 sail, well equipped, and manned by bold
and expert seamen.

To oppose this formidable fleet, Caesar ordered ships to be built on the
Loire, and the rivers running into it, exactly, as we have just stated,
after the model of the ships of the Vanni; for he was informed, or learnt
by experience, that the vessels which were used in the Mediterranean were
not fit for navigating and fighting on the ocean, but that such as were
employed on the latter must be built, not only stronger, but flat-bottomed,
and high at the head and stern, in order to withstand the fury of the waves
and winds, which was greater in the ocean than in the Mediterranean, and at
the same time to sail up the rivers, or in very shallow water, and to take
the ground, without injury or danger. Not being able, however, to build in
time a sufficient number of ships in Gaul, after the model of those of the
Vanni, he was under the necessity of bringing some from the south coast of
Gaul, and other parts of the Mediterranean Sea; he also collected all the
experienced pilots he could meet with, who were acquainted with the coasts,
and with the management of such ships, and exercised a sufficient number of
men at the oar, to navigate them.

These preparations were all indispensably requisite; for in the battle
which ensued, the Vanni and their allies fought their ships with a skill
and a valour of which the Romans had not had any previous example; and they
would certainly have been beaten, if they had not, by means of sharp
engines, cut the ropes and sails of the hostile fleet, and thus rendered
their ships unmanageable: in this state they were easily and speedily
captured. As the Vanni had on this occasion mustered all their forces,
their defeat put an end to their resistance, and removed Caesar's principal
obstacle to the invasion of Britain.