But they soon repented.
When in the following winter (697-698) Roman officers came to these legions to levy requisitions of grain there, they were detained by the Veneti as counter-hostages.

The example thus set was quickly followed not only by the Aremorican cantons, but also by the maritime cantons of the Belgae that still remained free; where, as in some cantons of Normandy, the common council refused to join the insurrection, the multitude put them to death and attached itself with redoubled zeal to the national cause.
The whole coast from the mouth of the Loire to that of the Rhine rose against Rome; the most resolute patriots from all the Celtic cantons hastened thither to co-operate in the great work of liberation; they already calculated on the rising of the whole Belgic confederacy, on aid from Britain, on the arrival of Germans from beyond the Rhine.
Caesar sent Labienus with all the cavalry to the Rhine, with a view to hold in check the agitation in the Belgic province, and in case of need to prevent the Germans from crossing the river; another of his lieutenants, Quintus Titurius Sabinus, went with three legions to Normandy, where the main body of the insurgents assembled.
But the powerful and intelligent Veneti were the true centre of the insurrection; the chief attack by land and sea was directed against them.

Caesar's lieutenant, Decimus Brutus, brought up the fleet formed partly of the ships of the subject Celtic cantons, partly of a number of Roman galleys hastily built on the Loire and manned with rowers from the Narbonese province; Caesar himself advanced with the flower of his infantry into the territory of the Veneti.
But these were prepared beforehand, and had with equal skill and resolution availed themselves of the favourable circumstances which the nature of the ground in Brittany and the possession of a considerable naval power presented.

The country was much intersected and poorly furnished with grain, the towns were situated for the most part on cliffs and tongues of land, and were accessible from the mainland only by shallows which it was difficult to cross; the provision of supplies and the conducting of sieges were equally difficult for the army attacking by land, while the Celts by means of their vessels could furnish the towns easily with everything needful, and in the event of the worst could accomplish their evacuation.

The legions expended their time and strength in the sieges of the Venetian townships, only to see the substantial fruits of victory ultimately carried off in the vessels of the enemy.
Naval Battle between the Romans and the Veneti Submission of the Maritime Cantons Accordingly when the Roman fleet, long detained by storms at the mouth of the Loire, arrived at length on the coast of Brittany, it was left to decide the struggle by a naval battle.